Choline administration reverses hypotension in spinal cord transected rats: the involvement of vasopressin.
Intracerebroventricular (i.c.v.) choline (50-150 microg) increased blood pressure and decreased heart rate in spinal cord transected, hypotensive rats. Choline administered intraperitoneally (60 mg/kg), also, increased blood pressure, but to a lesser extent. The pressor response to i.c.v. choline was associated with an increase in plasma vasopressin. Mecamylamine pretreatment (50 microg; i.c.v.) blocked the pressor, bradycardic and vasopressin responses to choline (150 microg). Atropine pretreatment (10 microg; i.c.v.) abolished the bradycardia but failed to alter pressor and vasopressin responses. Hemicholinium-3 [HC-3 (20 microg; i.c.v.)] pretreatment attenuated both bradycardia and pressor responses to choline. The vasopressin V1 receptor antagonist, (beta-mercapto-beta,beta-cyclopenta-methylenepropionyl1, O-Me-Tyr2, Arg8)-vasopressin (10 microg/kg) administered intravenously 5 min after choline abolished the pressor response and attenuated the bradycardia-induced by choline. These data show that choline restores hypotension effectively by activating central nicotinic receptors via presynaptic mechanisms, in spinal shock. Choline-induced bradycardia is mediated by central nicotinic and muscarinic receptors. Increase in plasma vasopressin is involved in cardiovascular effects of choline.
Savci
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Department of Pharmacology, Uludag University Medical Faculty, Bursa, Turkey. vsavci@uu20.bim.uludag.edu.tr
Ulus
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IH
D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D001285:Atropine / Q000008:administration & dosage / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D002794:Choline / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D006426:Hemicholinium 3 / Q000008:administration & dosage / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D007022:Hypotension / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013997:Time Factors; D014667:Vasopressins / Q000097:blood*
D065092:Antidiuretic Hormone Receptor Antagonists; D006727:Hormone Antagonists; D014667:Vasopressins; D001127:Arginine Vasopressin; D006426:Hemicholinium 3; C025043:vasopressin, 1-(1-mercaptocyclohexaneacetic acid)-2-(O- methyl-L-tyrosine)-8-L-arginine-; D001285:Atropine; D002794:Choline