ATP defendent Na+ transport and the characterization of Na+ / NH4+ exchange in basolateral vesicles of the blue crab, Callinectes sapidus, gill

ATP dependent Na+ transport was denonstrated in purified ba.solateral vesicles of the blue crab (Callinectes sapidus) gill. Active Na+ uptake was dependent upon the intravesicular presence of either K+ or NH; as a counterion. Final membrane preparations consist of inside-out basolateral vesicles, evidenced by intravesicular ouabain (1 rrM) and extravesicular vanadate (1 rnM) 22Na + uptake inhibition. Na+/NH4+exchange rates were investigated by detennining the NH; concentration in the recovered extravesicular nedium and by using the kinetic capabilities of a DU7 spectrophotareter. These purified basolateral membranes, rich in Na+,K+-ATPase activity, provide a useful in vitro tool for examining the stoichiaretry of Na+/NH4+transport in the blue crab gill