Effects of prostacyclin on hepatic vasculature and metabolism of renin in conscious dogs

Abstract

Prostaglandins have been implicated as important regulators of vascular resistance during high-renin states, and they act as potent stimuli for renin release. This study examines the effects of prostacyclin (PGI2) in conscious sodium-replete and -deplete dogs on the hepatic vasculature and on hepatic function and their role in determining the level of arterial plasma renin activity (PRA). Concurrent measurements of kidney function were made for comparison. Conscious trained dogs with chronic indwelling catheters were given intravenous infusions of PGI2. With a low dose of PGI2 (2 x 10(-8) g . kg-1 . min-1) hepatic blood flow increased while splanchnic vascular resistance fell. With a higher dose (8 x 10(-8) g . kg-1 . min-1) mean arterial pressure fell, and both hepatic and renal blood flow increased while splanchnic and renal resistances fell. The PGI2 infusion was accompanied by an increase in PRA. In both sodium-replete and -deplete animals the increases in PRA were accompanied by proportional increases in the hepatic extraction of renin and increases in the hepatic clearance of renin. Small but significant differences were found in the responses of sodium-replete and -deplete animals to PGI2 infusion. These results demonstrate that PGI2 has a potent influence on both the splanchnic and renal vasculatures and the hepatic clearance of renin and thus the role of the liver in determining hyperreninemia.