Adenosine triphosphate and muscular contraction and relaxation

Abstract

There are three observations which suggest that diminution of the adenosine triphosphate (ATP) content of muscle leads to contraction: (a) the ATP and creatine phosphate (CP) content of isolated striated muscle is about 5 times that of smooth muscle, and the latter always shows a state of partial contraction or tonus; (b) diminution of the ATP content of smooth muscle leads to contraction, and increase to relaxation; (c) adrenaline, which causes relaxation of smooth muscle, increases the ATP content of muscle by about 70 per cent in the first 15 sec.