BETA-1 AND BETA-2 ADRENOCEPTOR LIGAND AND MESSENGER-RNA EXPRESSION INDILATED CARDIOMYOPATHY

beta 1 and beta 2 adrenoceptor ligand activity has been shown to be do wn-regulated in failing myocardium. It is the aim of this study to tes t the hypothesis that also mRNA levels are down-regulated in dilated c ardiomyopathy. beta 1 and beta 2 adrenoceptor ligand activities and mR NA expressions were analyzed in left ventricular biopsies from six org an donor hearts, in papillary muscles from seven patients operated on for mitral regurgitation, and in six explanted hearts as the result of dilated cardiomyophathy. mRNA levels were determined by solution hybr idization. beta 1 ligand activity was decreased in the cases of mitral regurgitation (p<0.01) and dilated cardiomyopathy (p<0.001). beta 2 l igand activity did not differ between the three groups. mRNA expressio n was depressed in mitral regurgitation regarding both beta 1 (p<0.001 ) and beta 2 (p<0.01), while no differences were observed in dilated c ardiomyopathy as compared to the donor hearts. The regulation of beta 1 and beta 2 adrenoceptor ligand activity and mRNA expression appears to follow a specific pattern in dilated cardiomyopathy. The specific d own-regulation of beta 1 ligand activity seems to occur at a posttrans lational level.