Electrical membrane events underlying contraction of guinea pig bladder muscle

The relationship of electrical to mechanical activity of guinea pig bladder muscle has been studied in vitro by intracellular microelectrode and sucrose gap techniques. A discrete relationship between individual electrical action potentials and muscle contractions of small amplitude can be seen in muscle which is spontaneously active or stimulated by muscarinic activation or electrical current. An increase in the frequency of action potentials is associated with an increase in the frequency of small‐amplitude contractions and the generation of muscle tension. The frequency of action potential firing is sensitive to changes in the resting membrane potential of the muscle. The findings suggest that an increase in the frequency of action potential firing may be a major mechanism in the development of muscular tension in the wall of the bladder.