Evidence for an indirect cholinergic regulation of blood flow in the hypothalamus of conscious rabbits.
1 The effects of methacholine, atropine and adrenoceptor blockade on hypothalamic blood flow (HBF) were measured in conscious rabbits. 2 A dose of 1 microgram methacholine increased HBF while smaller and larger doses had no significant effect. 3 The vasodilatation induced by methacholine was blocked by atropine and by chemical sympathectomy of the hypothalamus with 6-hydroxydopamine. 4 The vasodilatation was reversed by propranolol but was not affected by phenoxybenzamine. 5 These results suggest that the vasodilator action of muscarinic receptor agonists on hypothalamic resistance vessels depends upon the integrity of a noradrenergic system, and is mediated via beta-adrenoceptors.
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology*; D007031:Hypothalamus / Q000098:blood supply* / Q000187:drug effects; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology*; D010643:Phenoxybenzamine; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects; D014980:Xenon Radioisotopes
D006892:Hydroxydopamines; D008688:Methacholine Compounds; D014980:Xenon Radioisotopes; D010643:Phenoxybenzamine; D001285:Atropine; D011433:Propranolol