Increases in alpha-but not beta-adrenoceptors in hypertrophied non-infarcted cardiac muscles from rats with chronic myocardial infarction.

The alteration in adrenoceptors in the hypertrophied right ventricle of the rats with myocardial infarction (Ml) was examined. The density of alpha-1-adrenoceptors increased in four and twelve week old Ml rats but not in one week old Ml rats. The beta-adrenoceptors did not significantly change. It is probable that the increased density of alpha-adrenoceptors may be one of the causes for the increased responsiveness to the alpha-adrenergic agonist in the hypertrophied cardiac muscles of Ml rats.