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M Gotsman

Publications and source records attributed to M Gotsman.

22 records · Page 2Linked to original sources
PubMedDate not supplied

Direct positive inotropic effect of mannitol on the intact canine heart.

Infusion of 25% mannitol into either the circumflex or left anterior descending coronary artery caused a significant increase in myocardial force development, measured by means of strain gauge in 10 anesthetized dogs. The changes were confined to the area perfused. The increase in developed force was dose-dependent, 20% at an infusion rate of 0.55 ml/min, 28% at 1.4 ml/min, 32% at 2.8 ml/min and 57% at 5.5 ml/min. There was a similar increase in dF/dt. The increase in developed force in the first minute was also dose-dependent, being 9% at 0.55 ml/min and 40% at 5.5 ml/min. No change in developed force occurred in the control (non-perfused) area or during saline infusion of the same artery at similar rates. A decrease in developed force of 10.5% was observed after the initial rise when mannitol was infused at 5.5 ml/min. This effect did not completely abolish the initial increase. No change in blood pressure, heart rate, LV systolic and diastolic pressure of LV dp/dt occurred during the experiment. It is concluded that doses of mannitol which are in clinical use have a direct positive inotropic effect on the intact canine heart.

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PubMedDate not supplied

Endogenous ouabain-like compound increases heart muscle contractility.

Cardiac glycosides such as digoxin or ouabain have long been known to influence the strength of contraction of cardiac muscle. Although the mechanism of action of these compounds remains unknown, all the proposed modes of action are based on initial binding to specific membrane receptors which are part of the (Na+ + K+)ATPase complex. These receptors, well characterized and defined, suggest the existence of an endogenous substance capable of binding to them, in analogy with endogenous opiates, discovered long after morphine and its receptors. As glycosides affect (Na+ + K+)ATPase activity, an endogenous substance may be a regulator of this important enzyme. Indeed, the search for endogenous regulators of the (Na+ + K+)ATPase or ouabain-like compounds (OLC) has recently intensified. These compounds, extracted and partially purified from mammalian brain, heart, blood and urine, and from toad skin and plasma, have been shown to inhibit 3H-ouabain binding and (Na+ + K+)ATPase activity. We report here that in addition to these effects, the OLC, highly purified from toad skin and sheep brain, increases the force of contraction of frog and guinea pig atrium.

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