Evidence for the Existence of a Functional Cardiac Renin-Angiotensin System in Humans

Background The presence of mRNA for the essential components of the renin-angiotensin system (RAS) has been found in animal and human hearts. The present study was designed to provide evidence for the existence of a (functional) cardiac RAS. Methods and Results Twenty-four patients with atypical chest pain undergoing coronary angiography for diagnostic purposes were investigated. The cardiac production rate of angiotensins was estimated by measurement of the cardiac extraction of 125I-angiotensin I and 125I-angiotensin II associated with the determination of endogenous angiotensins in aortic and coronary sinus blood in normal, low, or high sodium diets. In a normal sodium diet, angiotensin I and II aorta–coronary sinus gradients were tendentially negative (−1.8±2.5 and −0.9±1.7 pg/mL, respectively), and the amounts of angiotensin I and II added by cardiac tissues were 6.5±3.1 and 2.7±1.3 pg/mL, respectively. The low sodium diet caused a significant increase in both plasma renin activity (PRA) and angioten...