title: Cardiovascular receptors and calcium.
abstract: Sarcolemma-rich microsomal fractions were isolated from rabbit ventricular muscle by differential centrifugation and discontinuous sucrose gradient techniques. The fractions were characterized in terms of calcium binding, enzymic activity, gel electrophoresis, and ultrastructure. Racemate verapamil (1 microM) reduced (P less than 0.001) the Ca2+-binding and Ca2+-activated ATPase activity of these fractions; the activity resided in the l-isomer. 14C-Labeled verapamil was found to be bound to carbohydrate residues in the membrane. Pretreatment with trypsin or phospholipase C diminished the 14C-verapamil binding. When added to isolated hearts perfused under conditions of "low flow," verapamil prevented mitochondrial Ca2+ overload.
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D001665:Binding Sites; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D004594:Electrophysiology; D007473:Ion Channels; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008929:Mitochondria, Heart / Q000502:physiology; D011817:Rabbits; D012508:Sarcolemma / Q000378:metabolism / Q000502:physiology; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D000255:Adenosine Triphosphate; D014700:Verapamil; D007545:Isoproterenol; D002118:Calcium