ACCELERATION OF CONTRACTION BY BETA-ADRENOCEPTOR STIMULATION IS GREATER IN VENTRICULAR MYOCYTES FROM FAILING THAN NONFAILING HUMAN HEARTS

Myocytes from failing human ventricle contract and relax more slowly t han those from non-failing. This has been suggested to result from the lowering of basal cyclic AMP level in failing myocardium, and the con sequent withdrawal of a tonic lusitropic effect. We present data to su pport this hypothesis by demonstrating that the acceleration of contra ction and relaxation by beta-adrenoceptor stimulation is greater in my ocytes from failing than non-failing heart. This is despite the desens itisation of the inotropic effect of isoprenaline in the same failing cells. Following beta-adrenoceptor stimulation, speeds of contraction and relaxation are normalised in myocytes from failing heart, with fin al values not significantly different from non-failing.