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RITANSERIN AND SEROTONERGIC MECHANISMS IN BLOOD PRESSURE AND FLUID REGULATION IN SHEEP
Author(s) -
Nelson M.,
Coghlan J. P.,
Denton D. A.,
Tresham J. J.,
Whitworth J. A.,
Scoggins B. A.
Publication year - 1987
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1987.tb01874.x
Subject(s) - ritanserin , ketanserin , blood pressure , serotonergic , antagonist , phenylephrine , endocrinology , medicine , heart rate , serotonin , chemistry , 5 ht receptor , receptor
SUMMARY 1. In previous studies, exogenous serotonin (5‐HT), administered intravenously, caused dose‐related increases in mean arterial pressure and heart rate in conscious sheep. The 5‐HT 2 antagonist ketanserin (0.1 mg/kg per h, i.v.) was shown to lower blood pressure in the conscious sheep primarily through antagonism of α‐adrenoceptors. 2. A newer 5‐HT 2 antagonist, ritanserin, is a more selective antagonist in vivo , as it attenuated or abolished pressor responses to exogenous 5‐HT, but not to phenylephrine. 3. When infused alone, ritanserin (0.1 mg/kg per h, i.v.) failed to produce a decrease in blood pressure, suggesting that 5‐HT antagonistic properties are not sufficient by themselves to lower blood pressure. 4. Ritanserin displayed a different metabolic profile to ketanserin, with a markedly decreased water intake. The mechanism of this effect is unresolved, but may imply a permissive role for 5‐HT in the modulation of drinking responses in the sheep. 5. Ritanserin did not modify ACTH‐induced hypertension in sheep.