Abstract
It is evident from perfusion experiments on an isolated mammalian heart that this organ can functionate for several hours on its own stores of energy. Locke and Rosenheim 1 showed that the addition of glucose to the perfusion fluid produces a beneficial and sustaining effect upon the heart and that in turn this substance appeared to be actually utilized. More recently Hepburn and Latchford 2 have observed an increase in the sugar utilization of the isolated heart of over threefold when the pancreatic hormone was added to the perfusion fluid. These considerations indicate, therefore, that not only is the isolated heart capable of taking up carbohydrate for its activity but that its utilization of this substance is greatly augmented by insulin.
The energy requirements of the heart beating outside of the body are obviously much less than they are when in situ. Can the heart continue functional activity without impairment very long under the conditions of high pressure and rate prevailing in the body, when its supply of carbohydrate is practically cut off from the circulating blood and its own capacity for using up this substance is increased?
In the present experiments hypoglycemia was produced by giving large doses (20-30 units per kg.) of insulin. The activity of the heart was studied by means of intraventricular pressure and ventricular volume curves, and the electrocardiogram. The vascular system was studied by means of optically recorded central arterial pulse tracings.
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