Biophysical properties of the longitudinal smooth muscle of the XXXX rectum.

@entity4372 @entity969 @entity840
1. The membrane properties of the longitudinal muscle layer of the @entity840 rectum were studied in @entity4372 solution (twice the normal Krebs by addition of @entity969 ) by the micro-electrode technique. To produce the electrotonic potential and spike, stimulating partitions were used.2. @entity4372 solution hyperpolarized the membrane and increased the membrane resistance. However, no change in the space constant was observed before and after treatment with @entity4372 solution.3. The appearance and amplitude of the spike became regular after treatment with @entity4372 solution and appearance of the overshoot was consistent.4. The characteristic constants and the conduction velocity were measured in @entity4372 solution.(i) The space constant of the membrane was 0.81 mm, the time constant of the electrotonic potential was 83.7 msec and the time constant of the foot of the propagated spike was 8.8 msec.(ii) The conduction velocity of the excitation measured by insertions of the two micro-electrodes was 4.4 cm/sec.(iii) The chronaxie of the membrane was 71.3 msec.5. The results obtained from the present experiments were discussed in relation to the cable theory, and it was concluded that the passive properties of the membrane of the rectal smooth muscle could be explained by the cable equations.6. The specificities of the electrical properties of rectal smooth muscle were compared with muscle from other regions of the alimentary canal.
