title: Temperature dependence of verapamil action.
abstract: Ca2+-tolerant ventricular myocytes from adult rats were electrically stimulated. The maximal contraction frequency (fm) was determined at different temperatures. In drug-free Tyrode solution, fm follows the Arrhenius equation from 7 to 39.5 degrees C. However, verapamil introduces a discontinuity around 27 degrees C into the Arrhenius plot of fm. Above this transition temperature the calcium antagonist lowers fm more pronouncedly than below. Below, a tenfold higher concentration is needed for the same relative effect as at 37 degrees C. It is argued that this finding might be important in cardiac surgery when calcium antagonists are used for cardioplegia at deep hypothermia.
authors.forename: H M
authors.initials: HM
authors.lastname: Piper
authors.forename: R
authors.initials: R
authors.lastname: Koch
authors.forename: P G
authors.initials: PG
authors.lastname: Spieckermann
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D006352:Heart Ventricles / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000166:cytology*; D051381:Rats; D013696:Temperature; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D007473:Ion Channels; D014700:Verapamil; D002118:Calcium