We will investigate the effects of acute intravenous infusion of the hormone, angiotensin-(1-7), on cardiovascular function in healthy older adults in a randomized, double blind, placebo-controlled, crossover study.

Participation in this study will include three separate visits to the Clinical Research Center within the Penn State Milton S. Hershey Medical Center. Participants will first have a screening visit to determine if they are able to participate in this study. If eligible based on the screening visit, they will participate in two study visits separated by at least one week. At each study visit, they will be infused with doses of a placebo or angiotensin-(1-7) for about two hours. Before and at the end of the infusion, we will measure blood pressure and blood flow, nerve activity with an acupuncture-type needle in your leg, and collect blood samples from a small plastic tube (catheter) placed in the arm. Cells will also be collected from inside the vein using the catheter if the participant is willing. The study visits will include intravenous infusion of angiotensin-(1-7) or saline for approximately two hours, starting with increasing doses and holding at a steady-state dose. Endothelial function will be measured and blood samples and endothelial cells (if willing) will be collected at baseline and at the end of infusions. Blood pressure, heart rate, and muscle sympathetic nerve activity via microneurography will be measured throughout the study.

$25 per hour; additional $25 per study visit for cell collection