Effects of chronic hypoxia on the circulating and pancreatic renin-angiotensin system.

Abstract

The circulating renin-angiotensin system (RAS) plays a crucial role in the regulation of blood pressure, electrolytes, and fluid homeostasis. In contrast to the circulating RAS, the presence of an intrinsic RAS has been demonstrated in different tissues/organs, which may affect both local and global functions of a biologic system. Our previous studies provided solid evidence of the existence of a local RAS in rat pancreas. Our further investigation showed that such a pancreatic RAS could be activated by experimental models of chronic hypoxia and chemically induced pancreatitis. These previous findings formed the basis for the current study. Adult Sprague-Dawley rats were exposed to isobaric hypoxia (10% O2), and the effects on the circulating and pancreatic RAS were documented. The current study shows that exposure of rats to isobaric hypoxia caused a time-dependent increase in plasma renin activity. The activation of circulating RAS by hypoxia was associated with a parallel upregulation of local RAS components, including the mRNA expression of angiotensinogen and angiotensin II receptor types I and II in the pancreas. The upregulation of local pancreatic RAS, along with its counterpart circulating RAS, may be responsible for both physiologic and pathophysiologic aspects of a biologic system under chronic hypoxic stress.