Inotropic effect of noradrenaline and acetylcholine in the rabbit auricle studied by a cut-end method

Trans-gap application of noradrenaline or acetylcholine evoked pronounced inotropic but no chronotropic effects in spontaneously active rabbit auricle preparations. These results suggest the existence of intracellular receptors, both adrenergic and cholinergic, which were involved in the control of auricular contraction.