Reversal of the central hypotensive effect of clonidine by intracisternal curare-like agents.
Administration of tubocurarine, pancuronium, gallamine, or decamethonium into the cisterna magna of chloralosed dogs induced a rise in blood pressure. Clonidine (3 micrograms/kg) administered into the cisterna magna after tubocurarine, pancuronium, or gallamine significantly increased blood pressure; no significant change was found after decamethonium. The pressor response to clonidine after tubocurarine was antagonized by injection of the alpha 1-adrenoceptor-blocking agents AR-C 239 or prazosin into the cisterna magna at low doses prior to injection of clonidine. Yohimbine, a preferential alpha 2-adrenoceptor-blocking agent was ineffective. It is suggested that the pressor response to intracisternal clonidine after intracisternal tubocurarine is due to stimulation of alpha 1-adrenoceptor stimulation.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002946:Cisterna Magna; D003000:Clonidine / Q000037:antagonists & inhibitors*; D003650:Decamethonium Compounds / Q000494:pharmacology; D004285:Dogs; D005260:Female; D005703:Gallamine Triethiodide / Q000494:pharmacology; D006973:Hypertension / Q000139:chemically induced; D008297:Male; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D010197:Pancuronium / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D013268:Stimulation, Chemical; D014403:Tubocurarine / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D003650:Decamethonium Compounds; D003473:Neuromuscular Nondepolarizing Agents; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D010197:Pancuronium; D003000:Clonidine; D005703:Gallamine Triethiodide; D014403:Tubocurarine; D011224:Prazosin