title: The influence of calcium and beta-sympathomimetics on force-frequency relationship and resting potentiation in guinea pig papillary muscle.
abstract: The influence of various calcium concentrations and of the beta-sympathomimeticum orciprenaline (Alupent) on the force-frequency relationship and on the resting potentiation of isolated isometrically contracting papillary muscles of the guinea pig heart was studied. Elevation of Ca concentration and/or addition of orciprenaline augment the amplitudes of contractions elicited by rhythmical stimulation, but they diminish the amplitudes of test contractions elicited after a test interval of 1-2 s. It is suggested that calcium and orciprenaline strengthen the calcium loss from the sarcoplasmic reticulum out of the cell during a prolonged interval.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D009921:Metaproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects; D010210:Papillary Muscles / Q000187:drug effects; D012519:Sarcoplasmic Reticulum; D013997:Time Factors
chemical_list: D009921:Metaproterenol; D002118:Calcium