Differential beta adrenergic sensitivity of atrial and ventricular tissue assessed by chronotropic, inotropic, and cyclic AMP responses to isoprenaline and dobutamine.

Cat atrial tissue was more sensitive to isoprenaline (USP:isoproterenol) and dobutamine than ventricular tissue. Chronotropic response of atrial strips occurred at lower agonist concentrations than inotropic responses of papillary muscle. Cyclic AMP responses in atrial slices also occurred at lower agonist concentrations and were of much greater magnitude than the cyclic AMP responses in ventricular slices. However, the disporportionately greater sensitivity of atrial tissue was more marked with isoprenaline than with dobutamine.