Vascular Dysfunction in Black Individuals: Roles of Nitri... | NCT04770155

Vascular Dysfunction in Black Individuals: Roles of Nitri... | NCT04770155 | Trialant

Description Module

Detailed Description

Studies will be conducted in the Clinical Research and Trials Unit at the University of Mississippi Medical Center. All study visits will follow the same procedures, except for the drug or supplement being administered.

For Aim 1, double-blind, randomized, placebo-controlled crossover designs will examine the effects of increasing nitric oxide and cyclic guanosine monophosphate bioavailability on vascular function of young Black and White individuals. Three sets of two visits will be performed:

Aim 1a: At the beginning of each visit, participants will ingest either a nitrate-rich beetroot juice or a nitrate-depleted beetroot juice (serving as placebo) in their liquid commercial form, which has a distinct color and flavor. The nitrates will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
Aim 1b: Participants will receive a 7-day supplement of L-citrulline or placebo before each study visit, with a washout period of 7 days between visits. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide and L-citrulline, which is normally recycled back into L-arginine. Unlike L-arginine, oral ingestion of L-citrulline is not catabolized in the gut, nor is it extracted from systemic circulation through hepatic first-pass metabolism. Thus, ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine, increasing endothelium-dependent nitric oxide bioavailability.
Aim 1c: At the beginning of each visit, participants will ingest a liquid mixture prepared by Investigational Drug Services at the University of Mississippi Medical Center containing Sildenafil or placebo. Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.

For Aim 2, a double-blind, randomized, placebo-controlled crossover design will examine the role of endothelin-1 on the vascular function of young Black and White individuals. Two visits will be performed, with a minimum of 7 days between them.

• Aim 2: At the beginning of each visit, participants will ingest a liquid mixture prepared by Investigational Drug Services at the University of Mississippi Medical Center containing Bosentan or placebo. Bosentan blocks ETA and ETB receptors, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.

Arms/Interventions Module

Arm Groups

Label	Type	Description	Intervention Names
Beetroot juice (Aim 1a)	Active Comparator	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK).	Dietary Supplement: Dietary Nitrates 400 mg
Placebo (Aim 1a)	Placebo Comparator	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK).	Dietary Supplement: Dietary Nitrates 400 mg
L-citrulline (Aim 1b)	Active Comparator	Participants will receive pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit.	Dietary Supplement: L-citrulline 3 g
Placebo (Aim 1b)	Placebo Comparator	Participants will receive pills containing a placebo to take twice daily for 7 days before the study visit.	Dietary Supplement: L-citrulline 3 g
Sildenafil (Aim 1c)	Active Comparator	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5.

Interventions

Name	Type	Description	Arm Group Labels	Other Names
Dietary Nitrates 400 mg	Dietary Supplement	The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.

Outcomes Module

Primary Outcomes

Measure	Description	Time Frame
Flow-mediated Dilation	The percent change in arterial diameter normalized to arterial shear rate during reperfusion after 5 minutes of circulatory occlusion.	Within 4 hours of drug/supplement administration.
Reactive Hyperemia (Cuff Release)	Blood velocity area-under-the-curve from the beginning of reperfusion to return to resting values.	Within 4 hours of drug/supplement administration.
Muscle Hyperemia (Passive Leg Movement)	Peak and the area-under-the-curve of the change in femoral artery blood flow during 1 minute of passive leg movement.	Within 4 hours of drug/supplement administration.
Muscle Hyperemia (Rhythmic Handgrip Exercise)	Changes in brachial artery blood flow and conductance during single handgrip contractions at 3 intensities.	Baseline measurements with no drug/supplement administration before or after.
Muscle Hyperemia (Rhythmic Knee Extension Exercise)	Changes in femoral artery blood flow and conductance during 3 minutes of rhythmic knee extension exercise.	Within 4 hours of drug/supplement administration.

Contacts/Locations Module

Name	Affiliation	Role
Thales C Barbosa, Ph.D.	University of Mississippi Medical Center	Principal Investigator

Facility	Status	City	State	ZIP	Country	Contacts
University of Mississippi Medical Center		Jackson	Mississippi	39216	United States

References Module

Citations

PubMed Identifier	Type	Citation	Retractions
32783690	Background	Barbosa TC, Young BE, Stephens BY, Nandadeva D, Kaur J, Keller DM, Fadel PJ. Functional sympatholysis is preserved in healthy young Black men during rhythmic handgrip exercise. Am J Physiol Regul Integr Comp Physiol. 2020 Sep 1;319(3):R323-R328. doi: 10.1152/ajpregu.00105.2020. Epub 2020 Aug 12.
30118345	Background	Barbosa TC, Kaur J, Stephens BY, Akins JD, Keller DM, Brothers RM, Fadel PJ. Attenuated forearm vascular conductance responses to rhythmic handgrip in young African-American compared with Caucasian-American men. Am J Physiol Heart Circ Physiol. 2018 Nov 1;315(5):H1316-H1321. doi: 10.1152/ajpheart.00387.2018. Epub 2018 Aug 17.

Arm/Group Information

ID	Title	Description
FG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
FG001	Experimental: Placebo, Then Beetroot Juice (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
FG002	Experimental: L-citrulline, Then Placebo (Aim 1b)	Participants will receive pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit, or pills containing a placebo to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
FG003	Experimental: Placebo, Then L-citrulline (Aim 1b)	Participants will receive pills containing a placebo to take twice daily for 7 days before the study visit, or pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
FG004	Experimental: Sildenafil, Then Placebo (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5, or a liquid mixture containing a placebo. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
FG005	Experimental: Placebo, Then Sildenafil (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
FG006	Experimental: Bosentan, Then Placebo (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB, or a liquid mixture containing a placebo. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.
FG007	Experimental: Placebo, Then Bosentan (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.

Periods

Title

Milestones

Reasons Not Completed

Overall Study

Type	Comment	Milestone Data
STARTED	The only data collected were baseline measurements and no participants were ever given either intervention; the investigator was never able to obtain the treatments to use for the planned intervention arm of the study, resulting in its termination.	FG0001 subjects FG0011 subjects FG0021 subjects FG0031 subjects FG004
COMPLETED	The only data collected were baseline measurements and no participants were ever given either intervention; the investigator was never able to obtain the treatments to use for the planned intervention arm of the study, resulting in its termination.	FG0000 subjects FG0010 subjects FG0020 subjects FG003
NOT COMPLETED		FG0001 subjects FG0011 subjects FG0021 subjects FG0031 subjects FG004

Type	Comment	Reasons
Baseline measurements only. Investigator did not obtain treatments for the planned interventions.		FG0001 subjects FG0011 subjects FG0021 subjects FG003

Baseline Characteristics Module

Arm/Group Information

ID	Title	Description
BG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.

Units	Counts
Participants	BG000

Baseline Measures

Title	Description	Population Description	Parameter Type	Dispersion Type	Unit of Measure	Calculate Percentage	Denominator Units Selected	Denominators	Classes
Age, Categorical			Count of Participants

Outcome Measures Module

Outcome Measures

Type

Title

Description

Population Description

Reporting Status

Anticipated Posting Date

Parameter Type

Dispersion Type

Unit of Measure

Calculate Percentage

Time Frame

Units Analyzed

Denominator Units Selected

Arm/Group Information

Denominators

Classes

Analyses

Primary

Flow-mediated Dilation

The percent change in arterial diameter normalized to arterial shear rate during reperfusion after 5 minutes of circulatory occlusion.

Flow-mediated dilation was not collected in any participant.

Posted

Within 4 hours of drug/supplement administration.

ID	Title	Description
OG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.

Adverse Events Module

Arm/Groups

ID	Title	Description	Deaths (Affected)	Deaths (At Risk)	Serious Events (Affected)	Serious Events (At Risk)	Other Events (Affected)	Other Events (At Risk)
EG000	Beetroot Juice (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.

More Info Module

Certain Agreements

Title	Organization	Phone	Extension	Email
Director of Clinical Trials	University of Mississippi Medical Center	601-815-5000		clinicaltrials@umc.edu

Uploaded Document Information

Type	Includes Protocol	Includes SAP	Includes ICF	Document Label	Document Date	Document Uploaded Date	Document File Name
Prot_SAP	Yes	Yes	No	Study Protocol and Statistical Analysis Plan	Aug 10, 2021	Sep 11, 2023	Prot_SAP_000.pdf
ICF	No	No	Yes	Informed Consent Form	Aug 10, 2021	Sep 11, 2023	ICF_001.pdf

ID	Term
D006940	Hyperemia

ID	Term
D014652	Vascular Diseases
D002318	Cardiovascular Diseases

Intervention Browse Module

ID	Term
D002956	Citrulline
D000068677	Sildenafil Citrate
D000077300	Bosentan

ID	Term
D000599	Amino Acids, Diamino
D000596	Amino Acids
D000602	Amino Acids, Peptides, and Proteins
D013449	Sulfonamides

Race (NIH/OMB)

Count of Participants

Participants

Title

Denominators

Categories

Title	Measurements
American Indian or Alaska Native	BG0000 BG0010 BG0020 BG0030 BG0040 BG0050 BG0060 BG0070 BG0080
Asian	BG0000 BG0010 BG0020 BG0030 BG004
Native Hawaiian or Other Pacific Islander	BG0000 BG0010 BG0020 BG0030 BG004
Black or African American	BG0000 BG0010 BG0020 BG0030 BG004
White	BG0001 BG0011 BG0021 BG0031 BG004
More than one race	BG0000 BG0010 BG0020 BG0030 BG004
Unknown or Not Reported	BG0000 BG0010 BG0020 BG0030 BG004

Primary

Reactive Hyperemia (Cuff Release)

Blood velocity area-under-the-curve from the beginning of reperfusion to return to resting values.

Reactive hyperemia with cuff release was not collected in any participant.

Posted

Within 4 hours of drug/supplement administration.

ID	Title	Description
OG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG001	Experimental: Placebo, Then Beetroot Juice (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG002	Experimental: L-citrulline, Then Placebo (Aim 1b)	Participants will receive pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit, or pills containing a placebo to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG003	Experimental: Placebo, Then L-citrulline (Aim 1b)	Participants will receive pills containing a placebo to take twice daily for 7 days before the study visit, or pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG004	Experimental: Sildenafil, Then Placebo (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5, or a liquid mixture containing a placebo. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG005	Experimental: Placebo, Then Sildenafil (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG006	Experimental: Bosentan, Then Placebo (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB, or a liquid mixture containing a placebo. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.
OG007	Experimental: Placebo, Then Bosentan (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.

Units	Counts
Participants	OG0000 OG0010 OG0020 OG003

Primary

Muscle Hyperemia (Passive Leg Movement)

Peak and the area-under-the-curve of the change in femoral artery blood flow during 1 minute of passive leg movement.

Muscle hyperemia with passive leg movement was not collected in any participant.

Posted

Within 4 hours of drug/supplement administration.

ID	Title	Description
OG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG001	Experimental: Placebo, Then Beetroot Juice (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG002	Experimental: L-citrulline, Then Placebo (Aim 1b)	Participants will receive pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit, or pills containing a placebo to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG003	Experimental: Placebo, Then L-citrulline (Aim 1b)	Participants will receive pills containing a placebo to take twice daily for 7 days before the study visit, or pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG004	Experimental: Sildenafil, Then Placebo (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5, or a liquid mixture containing a placebo. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG005	Experimental: Placebo, Then Sildenafil (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG006	Experimental: Bosentan, Then Placebo (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB, or a liquid mixture containing a placebo. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.
OG007	Experimental: Placebo, Then Bosentan (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.

Units	Counts
Participants	OG0000 OG0010 OG0020 OG003

Primary

Muscle Hyperemia (Rhythmic Handgrip Exercise)

Changes in brachial artery blood flow and conductance during single handgrip contractions at 3 intensities.

The only data collected were baseline measurements and no participants were ever given either intervention; the investigator was never able to obtain the treatments to use for the planned intervention arm of the study, resulting in its termination. Upon resigning his Instructor position at UMMC, the investigator backed up the baseline data files on an external hard drive. Unfortunately, some issues with the external hard drive corrupted the files, making them no longer accessible.

Posted

Baseline measurements with no drug/supplement administration before or after.

ID	Title	Description
OG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG001	Experimental: Placebo, Then Beetroot Juice (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG002	Experimental: L-citrulline, Then Placebo (Aim 1b)	Participants will receive pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit, or pills containing a placebo to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG003	Experimental: Placebo, Then L-citrulline (Aim 1b)	Participants will receive pills containing a placebo to take twice daily for 7 days before the study visit, or pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG004	Experimental: Sildenafil, Then Placebo (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5, or a liquid mixture containing a placebo. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG005	Experimental: Placebo, Then Sildenafil (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG006	Experimental: Bosentan, Then Placebo (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB, or a liquid mixture containing a placebo. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.
OG007	Experimental: Placebo, Then Bosentan (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.

Units	Counts
Participants	OG0000 OG0010 OG0020 OG003

Primary

Muscle Hyperemia (Rhythmic Knee Extension Exercise)

Changes in femoral artery blood flow and conductance during 3 minutes of rhythmic knee extension exercise.

Muscle hyperemia with rhythmic knee extension exercise was not collected in any participant.

Posted

Within 4 hours of drug/supplement administration.

ID	Title	Description
OG000	Experimental: Beetroot Juice, Then Placebo (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG001	Experimental: Placebo, Then Beetroot Juice (Aim 1a)	Upon arriving at the laboratory, participants will ingest 140 ml of beetroot juice containing a low concentration (~0.0055 mmol) of nitrates (James White Drinks, Suffolk, UK), or 140 ml of beetroot juice containing a high (~12.8 mmol) concentration of nitrates (James White Drinks, Suffolk, UK). Dietary Nitrates 400 mg: The nitrates in the beetroot juice will be absorbed and reduced in the plasma to nitrite and nitric oxide, increasing endothelium-independent nitric oxide bioavailability.
OG002	Experimental: L-citrulline, Then Placebo (Aim 1b)	Participants will receive pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit, or pills containing a placebo to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG003	Experimental: Placebo, Then L-citrulline (Aim 1b)	Participants will receive pills containing a placebo to take twice daily for 7 days before the study visit, or pills containing 3 g of L-citrulline (Superior Labs, Park City, UT) to take twice daily for 7 days before the study visit. L-citrulline 3 g: Ingested L-citrulline becomes available in large quantities in the plasma for enzymatic conversion into L-arginine. The activity of the endothelial nitric oxide synthase converts L-arginine into nitric oxide, increasing endothelium-dependent nitric oxide bioavailability.
OG004	Experimental: Sildenafil, Then Placebo (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5, or a liquid mixture containing a placebo. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG005	Experimental: Placebo, Then Sildenafil (Aim 1c)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Sildenafil (100 mg), an inhibitor of phosphodiesterase 5. Sildenafil 100 mg: Sildenafil inhibits phosphodiesterase 5, an enzyme that degrades cyclic guanosine monophosphate in the vascular smooth muscle cells inactivating the nitric oxide-mediated signal; thus, Sildenafil will prolong the availability of cyclic guanosine monophosphate, enhancing the nitric oxide-mediated intracellular cascade.
OG006	Experimental: Bosentan, Then Placebo (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB, or a liquid mixture containing a placebo. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.
OG007	Experimental: Placebo, Then Bosentan (Aim 2)	Upon arriving at the laboratory, participants will ingest a liquid mixture containing a placebo, or a liquid mixture containing Bosentan (125 mg), a non-selective blocker of endothelin-1 receptors ETA and ETB. Bosentan 125 mg: Bosentan blocks endothelin-1 receptors ETA and ETB, leading to a reduction in vasoconstrictor tone and a greater magnitude of vasodilator responses.

Units	Counts
Participants	OG0000 OG0010 OG0020 OG003