A Factor Modifying Muscle Fibre Synæresis

Abstract

IN an attempt to extend observations on the synæresis of actomyosin by adenosine triphosphate to a less disorganized and more physiologically complete system, the volume changes which accompany the disappearance of the latter in a muscle fibre suspension are being studied. Small (2-gm.) samples of fresh rabbit psoas muscle are broken up in isotonic potassium chloride solution to particles of single-fibre diameter and approximately 1 mm. in length. This system has the advantage that, while a high degree of intrafibrillar organization is retained, such substances as salts, adenosine triphosphate and enzyme inhibitors are easily introduced and their effects on fibre-volume readily observed. The suspensions are spun in a centrifuge modified to permit continuous reading of the volume occupied by the fibres. Results so far obtained are here briefly summarized.