The utilization of various metabolites (blood fat and lactate, cardiac and lung glycogen) in the aglycaemic heart‐lung preparation

Abstract

IN studying the utilization of various metabolites by the heart in the heart-lung preparation, previous experimenters who have wished to obtain low sugar concentrations in the blood have done so either by the use of insulin or by allowing a sufficient lapse of time for the circulating sugar to disappear from the preparation. It appeared to us that it would be advantageous to adopt a method which avoids the use of insulin and also permits immediate observations when the preparation is functioning most efficiently, instead of waiting until such time as the sugar disappears. In such a preparation one would be able to determine readily the lactic acid consumption of the preparation by analysis of reservoir samples of blood without the necessary corrections for the amount of lactic acid added by red cells and by lungs to the circuit during the period of observation. The utilization of other substances by the heart can also be studied in such a heart-lung preparation perfused with sugar-free blood. Further, the rate at which they are used can be determined more accurately as they would not be competing with glucose or lactic acid, nor apparently, as will be discussed below, with any other normal source of cardiac energy present in any appreciable amount in the perfusing fluid. A preliminary report of investigations of this kind has already been published [Waters & Griffiths, 1936]. METHODS Sugar-free blood. Blood from a big donor dog anaesthetized with ether was prevented from clotting by the addition of a suitable amount of heparin. It was immediately centrifuged, and the plasma pipetted from the cells. The cells were well washed on the centrifuge with Ringer's

Fatty Change in the Myocardium of the Newborn

“…Only in conditions of great stress is glycogen called upon as an emergency fuel (Fletcher and Waters, 1938). If this is so, it may explain why extreme glycogen depletion was a late feature in some of our cases where fatty change was marked.…”

THE PHYSIOLOGICAL EFFECTS OF l-TYROSINE AND l-PHENYL-ALANINE ON THE RATE AND QUALITY OF PULSATION IN THE SEVENTY-TWO HOUR EXTIRPATED EMBRYONIC CHICK HEART

“…The electrolytic balance of Locke's solution is ideal for preserving the rhythmical pulsations of 72 hour chick hearts (1). Fletcher and Waters (2) report that mammalian heart muscle does not utilize dextrose when perfused with an artificial medium. The solution was prepared in triple distilled water, which had previously been boiled to remove excess carbon dioxide gas, and placed in a paraffin-lined bottle to prevent the silica of the glass from entering the solution.…”