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Patients with high aldosterone hormone have higher blood glucose than normal people. This study is being done to understand how aldosterone hormone affects the nerve activity that controls blood flow in the muscles and blood glucose. The information may be helpful in selecting blood pressure medications which can improve not only blood pressure but also improve blood sugar.
Patients with primary aldosteronism are known to have impaired insulin sensitivity, which is improved after removal of aldosterone-producing adenoma. In patients with essential hypertension, plasma aldosterone levels have been also shown to positively correlate with indices of insulin resistance.
Mechanism underlying aldosterone-induced insulin resistance is unknown. Aldosterone has been shown to interfere with insulin signaling the vascular cells by increasing production of reactive oxygen species via activation of NADPH oxidase, resulting in decreased availability of nitric oxide (NO), the key mediator for insulin-mediated vasodilation. Treatment with mineralocorticoid receptor antagonists has been shown to improve insulin sensitivity in mice with obesity and metabolic syndrome. Aldosterone has also been shown to increase resting sympathetic vasoconstrictor activity to the peripheral circulation. However, effects of aldosterone and mineralocorticoid receptor antagonists on insulin-mediated skeletal muscle vasodilation, sympathetic activation, and vascular oxidative stress have not been assessed in humans.
The investigators will collect venous endothelial cells, and measure skeletal muscle microvascular perfusion using Octafluoropropane microbubble contrast agents, and measure sympathetic nerve activity in normotensive controls (NT), stage 1 essential hypertensive subjects (ET), and patients with primary aldosteronism (PA) during hyperinsulinemic euglycemic clamp.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Hyperinsulinemic euglycemic clamp | Experimental | We will perform following procedures: DEFINITY® infusion Flow mediated vasodilation Endothelial cell collection Microvascular perfusion assessment using Definity Microneurography |
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| Initial Saline Infusion | Experimental | We will perform the following procedures: DEFINITY® infusion Human Recombinant Regular Insulin infusion Dextrose infusion Flow mediated vasodilation Endothelial cell collection Microvascular perfusion assessment using Definity Microneurography |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| DEFINITY® infusion | Drug | The DEFINITY® vial contains components that upon activation yield perflutren lipid microspheres, a diagnostic drug that is intended to be used for contrast enhancement during echocardiographic procedures. The vial contains a clear, colorless, sterile, non-pyrogenic, hypertonic liquid, which upon activation with agitation, provides a homogeneous, opaque, milky white injectable suspension of perflutren lipid microspheres. The suspension of activated DEFINITY® will be infused intravenously at a rate of 0.20 to 0.27 ml/min, not to exceed a maximum dose of 2 vials per study subject per day or visit. |
| Measure | Description | Time Frame |
|---|---|---|
| Increase in muscle sympathetic nerve activity during hyperinsulinemic euglycemic clamp | 1 day |
| Measure | Description | Time Frame |
|---|---|---|
| Change in microvascular blood flow during hyperinsulinemic euglycemic clamp. | 1 day | |
| Change in microvascular blood flow during saline infusion. | 1 day | |
| Change in endothelial cell protein expression after hyperinsulinemic euglycemic clamp |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Wanpen Vongpatanasin, MD | University of Texas Southwestern Medical Center | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| UT Southwestern Medical Center | Dallas | Texas | 75390 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 16822818 | Background | Catena C, Lapenna R, Baroselli S, Nadalini E, Colussi G, Novello M, Favret G, Melis A, Cavarape A, Sechi LA. Insulin sensitivity in patients with primary aldosteronism: a follow-up study. J Clin Endocrinol Metab. 2006 Sep;91(9):3457-63. doi: 10.1210/jc.2006-0736. Epub 2006 Jul 5. | |
| 19465546 | Background | Donato AJ, Gano LB, Eskurza I, Silver AE, Gates PE, Jablonski K, Seals DR. Vascular endothelial dysfunction with aging: endothelin-1 and endothelial nitric oxide synthase. Am J Physiol Heart Circ Physiol. 2009 Jul;297(1):H425-32. doi: 10.1152/ajpheart.00689.2008. Epub 2009 May 22. |
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| Human Recombinant Regular Insulin infusion | Drug | The plasma insulin concentration will be acutely raised and maintained at at a steady state by a prime-continuous insulin infusion. |
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| Dextrose infusion | Drug | The plasma glucose concentration will be held constant at 90 mg/dl by a variable glucose infusion during euglycemic hyperinsulinemic clamp |
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| Flow mediated vasodilation | Procedure | Flow mediated vasodilation (FMD), which is a non-invasive assessment of endothelial function, will be performed on the brachial artery using ultrasound. After a clear picture of the artery has been obtained, the cuff on the same arm will be inflated until it is tight for five minutes. During and following this, the subject's arm will continue to be imaged to monitor maximal increase in the brachial artery diameter. |
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| Endothelial cell collection | Procedure | We will collect endothelial cells from a superficial vein, usually in the arm. Following insertion of a peripheral intravenous (IV) catheter, we will collect cells from the inner lining of the vein using a thin, flexible J-tipped wire. The wire will be inserted through the IV into the vein and then removed, along with a sampling of endothelial cells. The cells collected will be processed and stained for several proteins involved in endothelial cell function, using immunofluorescent technique. |
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| Microvascular perfusion assessment using Definity | Procedure | Using high-resolution ultrasound, we will measure skeletal muscle blood flow during infusion of a solution containing the octafluoropropane microbubble contrast agent, Definity. The solution will be a dilution of 1 vial of Definity to 30 cc of normal saline. The ultrasound probe will be placed over the forearm to obtain images while octafluoropropane microbubbles (Definity) are infused intravenously at the rate of 0.20 to 0.27 ml/min, not to exceed a maximum dose of 2 vials per study subject per day or visit. The microvascular perfusion assessment using Definity be performed at rest as well as during slow and fast handgrip exercises. |
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| Microneurography | Procedure | Sympathetic nerve activity from the peroneal nerve measured by inserting a tiny needle directly into the nerve in the leg. Investigators will localize the nerve by electrical stimulation over the skin using a blunt probe. .The recording needle will remain in position throughout the study. |
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| 1 day |
| Change in endothelial cell protein expression after saline infusion | 1 day |
| Increase in muscle sympathetic nerve activity during saline infusion | 1 day |
| 17575088 | Background | Colussi G, Catena C, Lapenna R, Nadalini E, Chiuch A, Sechi LA. Insulin resistance and hyperinsulinemia are related to plasma aldosterone levels in hypertensive patients. Diabetes Care. 2007 Sep;30(9):2349-54. doi: 10.2337/dc07-0525. Epub 2007 Jun 15. |
| 20660053 | Background | Kontak AC, Wang Z, Arbique D, Adams-Huet B, Auchus RJ, Nesbitt SD, Victor RG, Vongpatanasin W. Reversible sympathetic overactivity in hypertensive patients with primary aldosteronism. J Clin Endocrinol Metab. 2010 Oct;95(10):4756-61. doi: 10.1210/jc.2010-0823. Epub 2010 Jul 21. |
| ID | Term |
|---|---|
| D006973 | Hypertension |
| ID | Term |
|---|---|
| D014652 | Vascular Diseases |
| D002318 | Cardiovascular Diseases |
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| ID | Term |
|---|---|
| D007328 | Insulin |
| ID | Term |
|---|---|
| D011384 | Proinsulin |
| D061385 | Insulins |
| D010187 | Pancreatic Hormones |
| D036361 | Peptide Hormones |
| D006728 | Hormones |
| D006730 | Hormones, Hormone Substitutes, and Hormone Antagonists |
| D010455 | Peptides |
| D000602 | Amino Acids, Peptides, and Proteins |
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