Lack of renal dopamine production during acute volume expansion in Dahl salt-sensitive rats.
Endogenous kidney dopamine (DA) is reported to contribute to the natriuretic response to acute volume expansion (VE). Several studies suggest that a defect in renal DA-ergic system may play a role in genetic hypertension in humans and rats. The present study was performed to determine the role of renal DA and tubular DA-1 receptors in the natriuretic response to VE in age-matched inbred Dahl salt sensitive (SS/Jr) and salt resistant (SR/Jr) rats of 9-11 weeks of age. In pentobarbital anesthetized rats, VE was carried out by intravenous infusion of isotonic sodium chloride (5% body weight) over a period of 60 min. This maneuver evoked marked increases in urine output and urinary sodium excretion in both SR/Jr and SS/Jr species. However, the natriuretic and diuretic response to VE was significantly reduced in SS/Jr as compared to SR/Jr rats. It was also observed that the urinary excretion of DA was significantly increased during VE only in SR/Jr, but not in SS/Jr rats. In separate group of animals, infusion of DA (1 microgram/kg/min) produced similar increases in urine output and urinary sodium excretion without causing any alterations in blood pressure or heart rate in either SS/Jr or SR/Jr rats. These results suggest that SS/Jr rats are not able to eliminate an acute increase in sodium load as efficiently as SR/Jr, which may be partly due to an impaired endogenous kidney DA production.
Sakamoto
T
T
College of Pharmacy, University of Houston, TX 77204-5515.
Chen
C
C
Lokhandwala
M F
MF
D000818:Animals; D004231:Diuresis / Q000187:drug effects; D004298:Dopamine / Q000096:biosynthesis* / Q000494:pharmacology; D004351:Drug Resistance; D007668:Kidney / Q000378:metabolism*; D008297:Male; D009318:Natriuresis / Q000187:drug effects; D051381:Rats; D011922:Rats, Mutant Strains; D012965:Sodium Chloride / Q000494:pharmacology*
D012965:Sodium Chloride; D004298:Dopamine