Tonomyosin of Arterial Muscle

Abstract

INVESTIGATION of the protein composition of cow carotids has shown that their muscular layer contains a new protein we have called tonoactomyosin, which does not superprecipitate at low ionic strength in presence of small amounts of adenosine triphosphate and remains soluble under these conditions. When ultra-centrifuged at 0.35 and neutral pH in presence of adenosine triphosphate, it splits into two peaks, a quick one assumed so far to be F-actin and a slow one sedimenting at about the rate of skeletal myosin. Tonoactomyosin appears to be soluble in the muscle sarcoplasm and seems thus responsible for the vascular tonus^1,2. A similar component can also be isolated from cow pregnant uteri³.