BLOCKADE OF THE BIOCHEMICAL CORRELATES OF CONTRACTION AND RELAXATION IN UTERINE AND INTESTINAL SMOOTH MUSCLE

The relationship between contraction and glycogen phosphorylase activation by adrenergic agents has been studied extensively in cardiac and skeletal muscle (see review by Haugaard & Hess, 1965). I t was suggested by Bulbring in 1960 that smooth muscle relaxation induced by epinephrine was a process requiring increased metabolic energy; and early results (Axelsson et al . , 1961) indicated tha t the action of epinephrine on the smooth muscle cell membrane might be related to its ability t o increase phosphorylase a activity. However, later reports concluded that the two effects were not related (Timms et al., 1962) and that, in fact, the increases in phosphorylase a activity seen in previous experiments were artifactual (Bueding et al., 1962). The present study is concerned with the effects of catecholamines and adrenergic blocking agents on the motility and phosphorylase activity of isolated rat uterus and guinea pig taenia coli.