Energy Exchange in Isometric Contraction of Vascular Smooth Muscle Induced by K‐ions

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Abstract
Acta physiol scand. 1969. 00. 000–000. – On isometric contraction of isolated mesenteric arteries induced by K‐ions in anaerobic, glucose‐free suspension solution the increase in tension after 1 min was accompanied by a significant decrease in the content of adenosine triphosphate (0.21 ± 0.07 μmoles/g), creatine phosphate (0.30 ± 0–08 μmoles/g) and an increased lactate content (0.25 ±0.10 μmoles/g) of the vascular muscle. In the presence of 0.5 % glucose, essentially the same effect was observed on the contents of energy‐rich phosphate esters, while the effect on the lactate content varied. Three min after the addition of K+ someresynthesis of energy‐rich phosphate compounds had taken place, but the synthesis was relatively slow. The series elastic component was relatively large in mesenteric arteries. Therefore even on isometric contraction the muscle performed work on stretching of this component. After correction of this “internal” work the LP ratio L.P/H was calculated to be 4.8, i. e. about 1/2 of that demonstrated by Hill (1958) in thermoelectrical determinations in isometrically contracted skeletal muscle from the frog. In glucose‐free solution a significant correlation was found between the tension developed and the content of energy‐rich phosphate compounds in muscle.