title: Control of intracellular calcium in heart muscle.
abstract: Regulation of the intracellular availability of Ca2+ in heart muscle cells is a necessary prerequisite for survival. Various subcellular organelles are involved, including the sarcoplasmic reticulum, the mitochondria, and the sarcolemmal complex. When isolated, the sarcolemmal complex forms either "inside-out" or "right-side-out" vesicles, and these have been used to study the regulatory role of the sarcolemma. Right-side-out vesicles exhibit passive Ca2+ binding that is inhibited by certain divalent cations including Ni2+, Co2+. By contrast, the binding that is exhibited by the inside-out vesicles is highly sensitive to H+ and cAMP. These findings will be discussed in accordance with the hypothesis that both the surface coat and the cytosolic surface of the plasmalemma play important roles in regulating the intracellular availability of Ca2+.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001826:Body Fluids / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D003326:Coronary Circulation; D007424:Intracellular Fluid / Q000201:enzymology*; D007473:Ion Channels / Q000378:metabolism*; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000201:enzymology*; D011817:Rabbits; D012508:Sarcolemma / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D007473:Ion Channels; D000262:Adenylyl Cyclases; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium