title: Critical remarks on the Ca-flux determinations in smooth and cardiac muscle.
abstract: The commonly used methods of determining Ca fluxes in smooth and cardiac muscle are scrutinized for their appropriateness. These methods include an incubation of the tissue in 45Ca, followed by a washout period either in ice-cold EGTA-containing Ca-free solutions or in lanthanum-containing Ca-free solutions. The amount of 45Ca remaining in the tissue at the end of the washout phase is taken as Ca2+ influx during the labeling period. Procedures including longer washout periods cannot yield information on Ca2+ influx, since the Ca store relevant for contractile activation rapidly adapts to changes in the extracellular Ca2+ concentrations.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005839:Gentamicins / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000378:metabolism*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*
chemical_list: D005839:Gentamicins; D002118:Calcium