Regional distribution of myocardial beta-adrenoceptors in the cat

The purpose of this study was to delineate the distribution of beta-adrenoceptor density in the cat heart, with an emphasis on areas within the left ventricle. beta-Adrenoceptor densities, determined for hearts obtained from five cats, were not significantly different in the left and rights atria, i.e. 47.6 +/- 7.2 and 32.8 +/- 7.5 fmol/mg protein, respectively. beta-Adrenoceptor densities for the septum and right ventricle were 105.4 +/- 15.0 and 65.0 +/- 14.0 fmol/mg protein, respectively. The beta-adrenoceptor density for the proximal distribution of the left anterior descending artery LV1, distal distribution of the left anterior descending artery LV2 and posterior wall of the left ventricle LV3 were: 81.3 +/- 11.5, 145.1 +/- 20.8 and 165.4 +/- 35.8 fmol/mg protein, respectively. Thus, the distribution of the beta-adrenoceptor densities was greatest in the apex of the left ventricle. The data suggest that there are regional differences in the beta-adrenoceptor densities among the areas of the heart and within the left ventricle. These differences may be related to functional differences.