[Positive inotropic action of plasma on the papillary muscle of rabbit heart].
Experiments on the papillary muscles of the rabbit heart were made to examine the effect of blood plasma on isometric contractions and intracellular rest potentials (RP) and action potentials (AP) of individual myocardial fibers. The replacement of the perfusate (Tyrode's solution) with plasma diluted with the solution (1:1) led to an increase in the amplitude of rhythmical contractions of the papillary muscles at stimulation frequencies of 0.1 to 2 Hz. The positive inotropic action of the plasma was accompanied by the shortening of the length of the intracellular AP. The increased amplitude of contractions does not appear to be associated with the action of catecholamines that might occur in the plasma, since the beta-adrenoblocker propranolol did not abolish the inotropic plasma effect. The removal (dialysis) of low-molecular plasma components with a molecular weight less than 50 000 daltons led to the elimination of the positive inotropic effect of the plasma. This allowed a suggestion that the factor that increases the contraction amplitude might occur in the low-molecular part of the plasma.
D000818:Animals; D002118:Calcium / Q000097:blood; D003956:Dialysis; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009119:Muscle Contraction; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000502:physiology*; D010477:Perfusion; D010949:Plasma / Q000502:physiology*; D011817:Rabbits
D002118:Calcium
Polozhitel'noe inotropnoe deĭstvie plazmy krovi na papilliarnuiu myshtsu serdtsa krolika.