title: Sources of calcium for ATP-induced contractions in rat urinary bladder smooth muscle.
abstract: Adenosine triphosphate (ATP 10(-4) M) induced monophasic contractions in preparations of rat urinary bladder strips. These responses were reversibly abolished in calcium (Ca2+)-free, ethyleneglycol-bis-(beta-amino-ethyl ether)-N,N'-tetra-acetic acid (EGTA 0.1 mM)-containing medium, and were partially inhibited by 10(-6) M verapamil (43%) and 10(-6) M diltiazem (32%). However, the inhibition of ATP-stimulated 45Ca uptake by verapamil and diltiazem was more pronounced (109 and 75%, respectively). The results suggest that, in addition to the primary role of extracellular Ca2+, intracellular Ca2+ is involved in ATP-induced contractions.
authors.affiliation: Division of Pharmacology and Toxicology, Indian Veterinary Research Institute.
authors.forename: M B
authors.initials: MB
authors.lastname: Bhat
authors.forename: S K
authors.initials: SK
authors.lastname: Mishra
authors.forename: V
authors.initials: V
authors.lastname: Raviprakash
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D004110:Diltiazem / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D051381:Rats; D001743:Urinary Bladder / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002132:Calcium Radioisotopes; D000255:Adenosine Triphosphate; D014700:Verapamil; D004110:Diltiazem; D002118:Calcium