The effects of dopamine on Na / K-ATPase activity in nerve ending membranes are prevented by N ethylmaleimide

G. RODRÍGUEZ DE LORES ARNAIZ; M. ANTONELLI DE GÓMEZ DE LIMA

NEUROCHEMISTRY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1983 vol. 5 p. 117 - 124

0197-0186

We have previously presented evidence for the existence of a brain soluble factor which mediates the stimulation of synaptosomal ATPases by catecholamines. The stimulation of synaptosomal ATPases by dopamine plus brain soluble fraction was not modified if the soluble fraction was heated for 5 min at 95°C. One day after preparation, the soluble factor inhibited the Na+, K+-ATPase, but not the Mg2+-ATPase activity, and subsequent addition of noradrenaline stimulated the ATPases activities. The inhibitory effect of a 24 h soluble fraction disappeared if the soluble fraction was dialyzed; in this case, noradrenaline did not activate the enzyme activities. Gel filtration in Sephadex G-50 permitted separating a subfraction which inhibited ATPase activity (peak II) from another which stimulated ATPase activity (peak I). Peak I stimulated both Na+, K+, and Mg2+ ATPases. Peak II inhibited only Na+, K+-ATPase, and when stored acidified, it mediated ATPases stimulation by noradrenaline.