Adenosine triphosphatase localization in the branchial heart of Sepia officinalis L. (Cephalopoda)

Summary Sodium- and potassium-dependent adenosine triphosphatase (Na⁺–K⁺-ATPase) is demonstrated in the branchial heart of Sepia officinalis L. by biochemical, cytochemical and autoradiographical methods. The biochemical data indicate the presence of Na⁺–K⁺-ATPase, shown by potassium and magnesium dependency and inhibition by ouabain. Cytochemically and autoradiographically, the enzyme is localized in the sarcolemma of the muscle cells. The positive reaction of the transparent cells (type I cells) is due to activity of alkaline phosphatases. The dark cells (type II cells) react negatively. In addition to the Na⁺–K⁺-ATPase, a magnesium-activated adenosine triphosphatase (Mg²⁺-ATPase) and a bicarbonate-stimulated ATPase (HCO₃^--ATPase) are localized in the mitochondria.This study was supported by the Deutsche Forschungsgemeinschaft and is part of the doctoral dissertation