The effects of ouabain and phenytoin on myocardial noradrenaline.
In guinea pigs, 160 mug kg-1 of ouabain decreased noradrenaline content of the right atrium and left ventricle by 44% and 68%, respectively, 2 hr after intraperitoneal injection. In rats, 20 mg kg-1 decreased noradrenaline content of the right atrium and left ventricle by 35% and 55%, respectively, at 1 hr. In mice, 10 mg kg-1 decreased myocardial noradrenaline by 33% and 20 mg kg-1 by 45% at 15 min. Phenytoin, 10 mg kg-1 in the guinea pig, 80 mg-1 in the rat, and 40 mg kg-1, in the mouse suppressed the effect of ouabain. Hexamethonium did not suppress the effect. In isolated, perfused guinea pig and rat hearts, 5.5 + 10-8 M and 6.8 + 10-6 M, respectively, caused an increase in noradrenaline output, which was usually followed by oscillatory fluxes; the initial increase in output was obtunded and the oscillations were entirely prevented by premedication with phenytoin but not by the addition of the drug to the perfusion medium.
D000818:Animals; D006168:Guinea Pigs; D006584:Hexamethonium Compounds / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D010042:Ouabain / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010477:Perfusion; D010672:Phenytoin / Q000494:pharmacology*; D051381:Rats; D013045:Species Specificity; D013997:Time Factors
D006584:Hexamethonium Compounds; D010042:Ouabain; D010672:Phenytoin; D009638:Norepinephrine