The short-term effect of captopril on salt and water intake in the rat is not taste-specific.
We have investigated the extent to which captopril's short-term (1 h) effects on salt and water intake in the rat are caused by effects on taste. In single-bottle tests a low dose of captopril (0.5 mg/kg s.c.), which blocks the synthesis of angiotensin II in the blood but not the brain, increased equally the intakes of water, 0.05, 0.15, 0.30 and 0.45 M NaCl, 0.3 M KCl, 10 mM HCl, 0.14 mM quinine hydrochloride and 0.1 mM saccharin solutions without changing the animals' preference for or aversion to each with respect to water. In two-choice tests this dose increased water but not 0.15 or 0.45 M NaCl intake. A large dose of captopril (100 mg/kg s.c.), to block the synthesis of angiotensin II also in the brain, did not enhance water or NaCl intake. Neither dose affected NaCl or water intake by rats drinking in response to 2 M NaCl, 5 ml/kg i.p. We conclude that during the first hour following injection captopril has no major effect on taste perception or preference in the rat and does not stimulate sodium appetite in the sodium-replete rat. Our results support the hypothesis that low doses of captopril increase fluid intake by enhancing the synthesis of angiotensin II in the brain.
D000804:Angiotensin II / Q000096:biosynthesis; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology*; D004326:Drinking / Q000187:drug effects*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012084:Renin-Angiotensin System / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology*; D013649:Taste / Q000187:drug effects*; D014868:Water Deprivation
D000804:Angiotensin II; D012965:Sodium Chloride; D002216:Captopril