Application of Adenosine Triphosphate and Related Compounds to Mammalian Striated and Smooth Muscle

Abstract

IN a former note¹ an account was given of the stimulating effect of adenosine triphosphate and related substances on the isolated striated frog muscle fibre. When adenosine triphosphate is applied to striated mammalian muscle (m. tib. ant. of the decerebrated cat) by close arterial injection² in amounts of 0·05–0·53 mgm. per gm. muscle (1·46–14·6 × 10^-6 mol./ml. = 0·1–1·0 × 10^-6 mol./gm. muscle) a rapid, tetanic contraction is released which is accompanied by interfering electrical activity (see accompanying record). Threshold dose and mechanical response are identical in non-curarized and curarized preparations, the effect of total curarization being insured by inexcitability of the sciatic nerve towards maximal stimuli and by insensitiveness of the muscle to intra-arterial injection of 50 μgm. acetylcholine. Intra-arterial injection of 5 μgm. acetylcholine after previous treatment of the non-curarized preparation with adenosine triphosphate releases a mechanical response with a considerably longer duration and higher tension than the same dose of acetylcholine does to a muscle without previous application of adenosine triphosphate.