Release of noradrenaline from the rat tail artery induced by inhibition of the sodium pump in calcium-free solution.
The release of noradrenaline from the isolated rat tail artery into Ca2+- and K-free, 1 mM ouabain containing solution was measured by means of radioenzymatic method. The rate of noradrenaline release increased gradually reaching a maximum of measured by means of radioenzymatic method. The rate of noradrenaline release increased gradually reaching a maximum of ca. 2.30 nmol.g-1.h-1 after 100 min. The enhancement of noradrenaline release could be inhibited by cocaine and phenoxybenzamine but not by desipramine. The rate of noradrenaline release could be approximately doubled by prior inhibition of monoamine oxidase with pargyline. The release was accompanied by a decline in the proportion of storage vesicles containing an electron-dense core. These observations indicate that, in the absence of external Ca2+, inhibition of the sodium pump causes nonexocytotic release of endogenous noradrenaline.
D000818:Animals; D001158:Arteries / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D003042:Cocaine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D010643:Phenoxybenzamine / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013623:Tail / Q000098:blood supply
D010643:Phenoxybenzamine; D010042:Ouabain; D012964:Sodium; D003042:Cocaine; D002118:Calcium; D003891:Desipramine; D009638:Norepinephrine