Central infusion of the AT1 receptor antagonist losartan inhibits thirst but not sodium appetite in cattle.
Experiments in cattle compared the effects of intracerebroventricular (i.c.v.) infusions of losartan and PD-123319 on water intake caused by water restriction, i.c.v. infusion of hypertonic NaCl, or i.c.v. infusion of angiotensin II (ANG II). The effects of these receptor antagonists on sodium intake caused by sodium depletion were also examined. Losartan infusion caused dose-dependent inhibition of the high water intake caused by the physiological stimulus of water restriction or by ANG II infusion but did not affect salt appetite. PD-123319 infused at equimolar or greater (in ANG II experiments) doses did not affect water intake or salt intake due to sodium depletion. The results of these i.c.v. infusion experiments confirm our earlier proposal that the physiological regulation of water intake in cattle may be mediated by ANG II acting centrally via AT1 receptors. The dose of losartan that inhibited thirst in cattle did not inhibit sodium appetite, nor did an equimolar dose of PD-123319.
Blair-West
J R
JR
Howard Florey Institute of Experimental Physiology and Medicine, Parkville, Victoria, Australia.
Denton
D A
DA
McKinley
M J
MJ
Weisinger
R S
RS
D000804:Angiotensin II / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001066:Appetite / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D001713:Biphenyl Compounds / Q000494:pharmacology*; D001921:Brain / Q000502:physiology*; D002417:Cattle; D002555:Cerebrospinal Fluid / Q000737:chemistry; D003681:Dehydration / Q000503:physiopathology; D004326:Drinking; D005260:Female; D006982:Hypertonic Solutions / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*; D007276:Injections, Intraventricular; D019808:Losartan; D011725:Pyridines / Q000494:pharmacology; D012964:Sodium / Q000172:deficiency; D013777:Tetrazoles / Q000494:pharmacology*; D013894:Thirst / Q000187:drug effects; D014868:Water Deprivation / Q000502:physiology
D057911:Angiotensin Receptor Antagonists; D001713:Biphenyl Compounds; D006982:Hypertonic Solutions; D007093:Imidazoles; D011725:Pyridines; D013777:Tetrazoles; D000804:Angiotensin II; C073402:PD 123319; D012964:Sodium; D019808:Losartan