Acceleration of contraction by beta-adrenoceptor stimulation is greater in ventricular myocytes from failing than non-failing human hearts.
Myocytes from failing human ventricle contract and relax more slowly than those from non-failing. This has been suggested to result from the lowering of basal cyclic AMP level in failing myocardium, and the consequent withdrawal of a tonic lusitropic effect. We present data to support this hypothesis by demonstrating that the acceleration of contraction and relaxation by beta-adrenoceptor stimulation is greater in myocytes from failing than non-failing heart. This is despite the desensitisation 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 final values not significantly different from non-failing.
Harding
S E
SE
National Heart & Lung Institute, Dept. Cardiac Medicine, London, UK.
Brown
L A
LA
del Monte
F
F
Davies
C H
CH
O'Gara
P
P
Vescovo
G
G
Wynne
D G
DG
Poole-Wilson
P A
PA
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D001706:Biopsy; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006333:Heart Failure / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D013268:Stimulation, Chemical; D016276:Ventricular Function
D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D007545:Isoproterenol; D002118:Calcium