Ultracytochemical demonstration of Ca(++)-ATPase activity in the rat cardiac muscle.

Ca(++)-activated adenosine triphosphatase (Ca(++)-ATPase) was investigated in the rat cardiac muscle at neutral pH using tricine buffer. Reaction products indicating Ca(++)-ATPase activity were localized on the myocardial sarcolemma, sarcoplasmic reticulum, myofilaments, luminal and abluminal surfaces of capillary endothelium plasmatic membrane. The verification of the main enzymatic characteristics of Ca(++)-ATPase localization activity using this cytochemical procedure is under discussion.