Energetics of Isometric and Isotonic Contraction in Isolated Vascular Smooth Muscle under Anaerobic Conditions

AbstractLundholm, L. and E. Mohme‐Lundholm. Energetics of isometric and isotonic contraction in isolated vascular smooth muscle under anaerobic conditions. Acta physiol. scand. 1965. 64. 275–282. –In experiments on isolated bovine mesenteric artery the energy production was determined from the lactic acid production under anaerobic conditions. During isometric contraction of the muscle preparations, addition of adrenaline or of potassium ions resulted in a 3‐ to 5‐fold elevation of the metabolism concomitant with a rise of tension. When the tension had reached maximal level, the metabolic elevation was more moderate ‐ approximately 60 per cent in the experiments with adrenaline and about 20 per cent in those with potassium ions. Thus the muscle consumed more energy in attaining a certain tension level than in maintaining it. Total consumption of high energy phosphate compounds on isometric contraction was estimated to exceed the preformed content by approximately 300 per cent. The energy demand was appreciably greater for isometric than for isotonic contraction, both during the increasing tension phase and during maintenance of constant tension. – Dibenamine blocked the metabolic stimulating and the contractile effects of adrenaline, but not the effects of potassium ions.