Effect of sodium deficiency of the action potential of the smooth muscle of ureter

¹ Department of Physiology, School of Medicine, Hiroshima University, Hiroshima, Japan

Action potentials of the smooth muscle of cat ureter were studied by using ultramicroelectrodes. Among 193 penetrations, the resting potential averaged 45 mv and the amplitude of action potential 32 mv. In four instances a slight overshoot was recorded. Action potential consisted of a relatively rapid rising phase followed by a slow repolarization phase, and its duration was about 0.3 sec. Effects of sodium deficiency on action potential were studied by using three different sodium substitutes. Both the height and the rising rate of action potential decreased as the concentration of extracellular sodium was reduced, indicating that the action potential of ureter muscle can be explained on the basis of sodium theory. The duration of the action potential was prolonged when sucrose or choline chloride was used as a sodium substitute; on the other hand, it shortened when tris chloride was employed. The essential role of sodium ions in the development of the action potential in ureter muscle is discussed.

Key Words: nerve impulse transmission • conduction velocity block conduction of excitation • cell membrane excitability • effect of sodium substitutes on conduction velocity • sodium deficiency in smooth muscle

Submitted on March 26, 1963

This article has been cited by other articles:

				H. KURIYAMA, K. KITAMURA, T. ITOH, and R. INOUE Physiological Features of Visceral Smooth Muscle Cells, With Special Reference to Receptors and Ion Channels Physiol Rev, July 1, 1998; 78(3): 811 - 920. [Abstract] [Full Text] [PDF]