title: The opposed influences of beta-adrenergic stimulation and adenosine on the frequency-force relationship of isolated left atria of guinea-pigs.
abstract: The normal frequency-force relationship of left guinea-pig atria can be largely suspended when strong beta-adrenergic stimulation by orciprenaline is antagonized by the negative inotropic effect of adenosine, so that contraction amplitude is nearly equal at an intermediate level over a wide range of stimulation rates. Curves obtained with new method for recording continuous frequency-force loops are presented.
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D006325:Heart Atria / Q000187:drug effects; D008297:Male; D009921:Metaproterenol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051379:Mice; D009200:Myocardial Contraction / Q000187:drug effects*
chemical_list: D009921:Metaproterenol; D000241:Adenosine