[Do cardioselective beta-antagonists block the cardiac beta-receptor function also in the long run?]

As the human cardiomyocyte expresses both beta 1 and beta 2 adrenoceptors it is to be expected that the inhibition of one species of receptors can be counteracted by the other. This hypothesis was tested in 40 middle-aged men scheduled for coronary artery bypass surgery. Half the patients had been treated with cardioselective beta 1 antagonists for more than three months while the 20 control patients had never been beta-blocked. The haemodynamic status after induction of a standardized fentanyl/midazolam anaesthesia and the sensitivity of the cardiovascular beta-adrenoceptors to isoprenaline titration were similar in both groups. In conclusion, patients chronically treated with cardioselective beta 1-blockers compensate for the perturbation to such a degree that their cardiovascular function is indistinguishable from patients who have never received beta-blockers.