The cardic effects of higenamine were studied in isolated guinea pig atrium Higenamie increased the contract, excitadlity ahd automaticity, shortened the functional refractory period, which were similar to isoprenaline, but the efficacy of higenamine was lower than that of the latter, propranolol shifted the concentration-response curvefor higenamine to incrcase the beating rate of right (?) in right parallely and the maximum response remained unchanged. In addition, higenamine enhanced the positive stairca...