Partial characterization of an endogenous factor which modulates the effect of catecholamines on synaptosomal Na+, K+ ATPase

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

NEUROCHEMICAL RESEARCH

SPRINGER/PLENUM PUBLISHERS

Año: 1986 vol. 11 p. 933 - 947

0364-3190

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.Special Issue dedicated to Prof. Eduardo De Robertis.