Beta-blockade in the ischemic reperfused working rabbit heart: dissociation of beta-adrenergic blocking and protective effects.

The cardioprotective effects of the beta-blocking drugs (dl-nebivolol, d-nebivolol, propranolol, atenolol, dilevalol and pindolol) were tested in the isolated working rabbit heart. The effects of l-nebivolol, having little beta-adrenoceptor blocking activity, were also studied. The hearts were subjected to 25 min ischemia, followed by 30 min of reperfusion. In solvent-treated hearts, ischemia resulted in a considerable loss of function. The mean functional recovery of one of the most sensitive parameters, i.e. aortic flow, was only 6%. Pretreatment either with dl-nebivolol, d-nebivolol, l-nebivolol or propranol significantly improved cardiodynamic function. Recovery after pretreatment with atenolol, dilevalol and pindolol (less than 10 mg/l) was not significantly improved when compared to solvent-treated hearts. The results suggest that the protective effects of some beta-blockers are most probably not related to beta-adrenoceptor blocking activity.