[Effects of somatotropic hormone on Na, K-ATPase of the synaptosomal membrane of the young rat brain].

Human somatotropic hormone (STH), starting from a concentration of 5.10(38) M, was found to inactivate in vitro (by 37%) the Na, K-ATPase activity of osmotically disrupted synaptosomes from 3-week-old rat brain. The inhibitory effect of STH was stronger with higher concentrations. The synaptosomal Mg- and Ca-ATPase activities were stimulated by STH (5.10(-9)-5.10(-6) M). Only at a concentration of 5.10(-6) M STH did inactivate the synaptosomal Na, K-ATPase from the adult rat brain.