Physiology of the Smooth Muscles of the Bladder and Urethra

I. INTRODUCTION Most of what is known of smooth-muscle function generally comes from study of smooth muscle from other tissues, particularly vascular smooth muscle, and this may be related to research-funding priorities. Many excellent reviews of detailed aspects of smooth-muscle function in general have been produced recently (1-9), and we know much about the membranes of smooth-muscle cells, how they are excited, either electrically or by ligand binding to membrane receptors, how the membrane signal is transduced to the contractile apparatus by second-messenger systems, and how contractile protein function is regulated.