Role of brain angiotensin II in thirst and sodium appetite of sheep.
The contribution of brain angiotensin II (ANG II) to thirst and Na+ appetite of sheep was evaluated. Thirst was stimulated by water deprivation, intracarotid or intracerebroventricular infusion of ANG II, or intracarotid or intracerebroventricular infusion of hypertonic solution. Intracerebroventricular infusion, over 1-3 h, of the ANG II type 1 (AT1) receptor antagonist, losartan, decreased or abolished water intake caused by all of the stimuli tested. Intracerebroventricular infusion of ZD-7155, another AT1-receptor antagonist, blocked ANG II-induced water intake. Neither losartan nor ZD-7155 infused intracerebroventricularly altered the Na+ appetite of Na(+)-depleted sheep. Intracerebroventricular infusion of losartan over 3 h, however, did block the increase in water intake and the decrease in Na+ intake caused by intracerebroventricular infusion of hypertonic NaCl in Na(+)-depleted sheep. Intracerebroventricular infusion of the ANG II type 2 (AT2) receptor antagonist, PD-123319, over 1-3 h, did not alter ANG II-induced water intake or Na+ depletion-induced Na+ intake. These results are consistent with the proposition that brain ANG II, working via AT1 receptors, is involved in the neural system controlling some aspects of physiological thirst and Na+ appetite. A role for AT2 receptors in physiological thirst or Na+ appetite is not supported by the present results.
Weisinger
R S
RS
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
Blair-West
J R
JR
Denton
D A
DA
Tarjan
E
E
D000704:Analysis of Variance; D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology / Q000502:physiology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D001713:Biphenyl Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D001921:Brain / Q000502:physiology*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology; D003681:Dehydration / Q000503:physiopathology; D004039:Diet, Sodium-Restricted; D004231:Diuresis / Q000187:drug effects; D005260:Female; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D007263:Infusions, Parenteral; D019808:Losartan; D008353:Mannitol / Q000008:administration & dosage / Q000494:pharmacology; D009287:Naphthyridines / Q000008:administration & dosage / Q000494:pharmacology*; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology; D012463:Saliva / Q000187:drug effects / Q000378:metabolism; D012756:Sheep; D012982:Sodium, Dietary; D013777:Tetrazoles / Q000008:administration & dosage / Q000494:pharmacology*; D013894:Thirst / Q000187:drug effects / Q000502:physiology*
D057911:Angiotensin Receptor Antagonists; D001713:Biphenyl Compounds; D007093:Imidazoles; D009287:Naphthyridines; D011725:Pyridines; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D012462:Saline Solution, Hypertonic; D012982:Sodium, Dietary; D013777:Tetrazoles; C095905:ZD 7155; D000804:Angiotensin II; C073402:PD 123319; D008353:Mannitol; D019808:Losartan