Our bodies respond differently to stress. Animal studies by the investigators have found that endothelin-1 plays a role in regulating blood pressure in response to stress. This study is an extension of the investigators previous animal work to evaluate the role of endothelin-1 during stress in humans.

Using a salt sensitive animal model of prehypertension, the Dahl S rat,the investigators have previously published that acute stress elicits a pressor response that is accompanied by an increase in 8 isoprostane and endothelin-1. However, the pressor response is suppressed by endothelin A/B receptor antagonism. Moreover, the investigators have identified that the increase in 8-isoprostane occurs downstream of endothelin receptor activation. These data indicate that endothelin receptor activation is a main player In the pressor response to acute stress in pre-hypertensive animals; however, this phenomenon has yet to be elucidated in humans.

Inclusion Criteria:

• Men and premenopausal women (Ages 18-50 years old)
• Self-reported Black and White adults
• Lean adults (BMl <25 kg/m^)
• Obese adults (BMl > 30 kg/m^)

Exclusion Criteria:

• Having a BMI less than 16 kg/m2 (severely and very severely underweight) or that is greater than 40 kg/m2 (Class III obesity)
• Having evidence of cardiovascular, pulmonary, renal, hepatic, cerebral, or metabolic disease
• Having evidence of pregnancy
• Using medications that affect vascular tone (i.e., nitrates, etc.)
• Postmenopausal women
• Uncontrolled hypertension
• Individuals who are on a restricted salt diet
• Having a history of chronic pain
• Having a history of rheumatoid arthritis
• Using medications that are contraindicated with bosentan (i.e. glyburide, cyclosporine)
• Liver dysfunction (which may be identified with the blood sample we take)