Influence of catecholamines on the in vivo release of histamine in the hypothalamus.
The hypothalamus of conscious, freely moving rats was superfused with artificial CSF through push-pull cannulae and the release of endogenous histamine was determined radioenzymatically in the superfusate. Superfusion with potassium chloride enhanced the release rate of histamine. The effect of potassium chloride was abolished by alpha-fluoromethylhistidine. Noradrenaline (alpha 1- and alpha 2-agonist) and clonidine (alpha 2-agonist) decreased the release rate of histamine and inhibited the potassium-induced histamine release. In preliminary experiments, yohimbine (alpha 2-antagonist) seemed to increase the release rate of histamine in the superfusate. beta-Agonists and antagonists (isoprenaline, salbutamol, propranolol) did not influence the release of histamine.
Prast
H
H
Department of Pharmacodynamics and Toxicology, University of Innsbruck, Austria.
Heistracher
M
M
D000818:Animals; D002395:Catecholamines / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D006636:Histamine Release / Q000187:drug effects*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D015016:Yohimbine / Q000494:pharmacology
D002395:Catecholamines; D006633:Histamine Antagonists; D008762:Methylhistidines; D015016:Yohimbine; D011189:Potassium Chloride; C028309:alpha-fluoromethylhistidine; D003000:Clonidine; D009638:Norepinephrine