Cardiovascular effects of serotonin and DP-5-CT in conscious Long-Evans and Brattleboro rats.
The regional hemodynamic changes caused by intracerebroventricular 5-hydroxytryptamine (5-HT) were investigated in conscious Long-Evans and Brattleboro rats with chronically implanted Doppler flow probes. In both strains, a low dose of 5-HT (4 nmol/kg) caused a pressor response associated with tachycardia, mesenteric vasoconstriction, and a transient hindquarters vasodilatation. In Long-Evans rats, higher doses of 5-HT (40 and 120 nmol/kg) caused a pressor response, a bradycardia, mesenteric vasoconstriction, and maintained hindquarters dilatation. The bradycardia and mesenteric vasoconstriction caused by 40 nmol/kg of 5-HT in Long-Evans rats were attenuated by d(CH2)5Tyr(Me)arginine vasopressin, a V1-receptor antagonist. In Brattleboro rats the high doses of 5-HT failed to cause a pressor response but caused a delayed depressor response, a transient tachycardia, less mesenteric vasoconstriction, and a larger initial hindquarters dilatation compared with Long-Evans rats. The initial part of the hindquarters vasodilator response caused by 120 nmol/kg of 5-HT in Brattleboro rats was attenuated by the beta 2-adrenoceptor antagonist ICI-118551. In Long-Evans rats, N,N-di-n-propyl-5-carboxamidotryptamine maleate (DP-5-CT; 3, 30, and 100 nmol/kg icv), a 5-HT1A receptor agonist, caused a tachycardia associated with a marked hindquarters vasodilatation. These changes were accompanied by a weak mesenteric vasoconstriction and, for the highest dose of DP-5-CT, a pressor response. These data overall are consistent with the hemodynamic effects of intracerebroventricular 5-HT contingent on vasopressin release and, along with DP-5-CT, sympathoadrenal excitation; however, additional mechanisms are indicated.
Anderson
I K
IK
Department of Physiology and Pharmacology, University of Nottingham Medical School, Queen's Medical Centre, United Kingdom.
Ramage
A G
AG
Gardiner
S M
SM
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D002319:Cardiovascular System / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D006727:Hormone Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D011910:Rats, Brattleboro; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014363:Tryptamines / Q000494:pharmacology*
D000319:Adrenergic beta-Antagonists; D065092:Antidiuretic Hormone Receptor Antagonists; D006727:Hormone Antagonists; D011412:Propanolamines; D017366:Serotonin Receptor Agonists; D014363:Tryptamines; D001127:Arginine Vasopressin; D012701:Serotonin; D012965:Sodium Chloride; C026777:ICI 118551; C025043:vasopressin, 1-(1-mercaptocyclohexaneacetic acid)-2-(O- methyl-L-tyrosine)-8-L-arginine-; C055895:N,N-dipropylcarboxamidotryptamine