[Effect of increased mechanical loading on the relation between the contraction of isolated cardiac muscle and the concentration of Ca++ in the perfusate].
The distension of isolated papillary muscles working isotonically or a transition to isometric working entailed an increased sensitivity of the contractile velocity to changes in perfusate Ca++ concentration. After sudden fall in Ca++ concentration, a more rapid decline of the contractile velocity in isometric mode was observed as compared to isotonic mode of working. The similar difference was found in experiments on isolated guinea pig heart working in isovolumic or auxotonic modes, though the rate of Ca++ loss by the heart was the same. The results suggest that an increased mechanical load may diminish the ability of myocardial cells to compensate for the changes in external Ca++.
D000818:Animals; D001696:Biomechanical Phenomena; D002118:Calcium / Q000032:analysis / Q000502:physiology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000032:analysis; D007537:Isometric Contraction; D007551:Isotonic Contraction; D009200:Myocardial Contraction; D009206:Myocardium / Q000032:analysis; D010210:Papillary Muscles / Q000502:physiology; D012964:Sodium / Q000502:physiology
D012964:Sodium; D002118:Calcium
Vliianie povyshennoĭ mekhanicheskoĭ nagruzki na zavisimost' sokrashcheniia izolirovannoĭ serdechnoĭ myshtsy ot kontsentratsii Ca++ v perfuzate.