BIOPHYSICAL STUDIES OF THE INTESTINAL SMOOTH MUSCLE CELLS.
Abstract
The membrane potentials of longitudinal muscles of the duodenum, jejunum, ileum, caecum and rectum varied from 54 to 56 mV and those of circular muscles varied from 57 to 60mV. Overshoot potentials could be observed in all regions of the intestine. The maximum rate of rise of these potentials varied from 11 to 18 V/sec. The conduction velocities in the longitudinal muscles of jejunum and rectum were 2.1 cm/sec and 4.0 cm/sec respectively. Chronaxies of the longitudinal muscles of jejunum and stimulation of the single cells of the duodenum and caecum could trigger a spike, similar to that observed in the taenia coli. The effective membrane resistance and the time constant for the longitudinal muscles were 40-50 mega ohms and 3-5 msec respectively. The effects of various chemical agents on the membrane activities were as follows. (a) Atropine slightly hyperpolarized the membrane and reduced the slow potential changes. Prostigmine depolarized the membrane and enhanced the slow potential changes. (b) Ba(2+) depolarized the membrane and enhanced the slow potential changes. Atropine and tetrodotoxin partially prevented the action of Ba(2+) on the membrane activities. Effects of chemical agents on the membrane activity elicited by electrical stimulation were as follows. (a) Short pulse stimulation generated the spike as direct response of the muscle cell membrane, then it was followed by slow depolarization, delayed hyperpolarization, and post-inhibitory rebound. (b) The slow depolarization and the post-inhibitory rebound were reduced in amplitude by treatment with atropine, and enhanced by treatments with prostigmine and Ba(2+). Tetrodotoxin blocked all activities except the spike. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1968
- Accession Number
- AD0667389
Entities
People
- Naoki Toida
Organizations
- Kyushu University