[ATP regeneration in the outer segments of frog photoreceptors]

The outer segments of retinal photoreceptors of the frog Rana temporaria were found to possess the adenylate kinase and creatine phosphokinase activities. It was shown that the activities found are not due to contaminations by the fragments of inner photoreceptor segments and pigment epithelium processes which are in direct contact with outer segments. The absolute value of the ATP resynthesis rate exceeds the rate of its hydrolysis. It is concluded that ATP synthesis in the creatine phosphokinase and adenylate kinase reactions is one of the pathways of ATP regeneration in vivo.