S-Space College of Medicine/School of Medicine (의과대학/대학원) Dept. of Medicine (의학과) The Seoul Journal of Medicine The Seoul Journal of Medicine Vol. 29 No.3 (1988)
Effects of Extracellular Sodium on the Slow Wave of the Antral Smooth Muscle in Guinea Pig Stomach
세포의 NA+농도 변화가 기니피그 위 평활근 서파에 미치는 영향
- Lee, Sang Jin; Kim, Ki Whan; Kim, Woo Gyeum
- Issue Date
- Seoul J Med, Vol.29 No.3, pp. 227-236
- The characteristics of contractile and electrical responses to various concentrations
of extracel1ular sodium in the antrum of guinea-pig stomach were investigated in order
to elucidate the mechanisms generating and control1ing the slow wave which is known to be
responsible for the gastric motility. The results obtained were as fol1ows:
1) Tonic contraction increased as the concentration of extracel1ular sodium decreased.
However, phasic contraction gave a different response around 10 mM Na +.
2) In Na + -deficient solutions, prolongation in the second component and potentiation in
the spike component of the slow wave and membrane depolarization were observed, Those
changes became more marked with each decrement of Na + concentration.
3) In solutions below 10 mM Na +, small slow waves whose components could not be
clearly distinguished appeared at a faster frequency than it did in normal Tyrode solution.
4) In the presence of guanethidine and atropine the change described in 3) disappeared in
solutions of Na + concentration below 10 mM. Instead the same responses as described in 2)
From the above results following conclusions can be made: As the concentration of extracel1ular
sodium decreases the configuration of the slow wave of the antral smooth muscle
in guinea-pig stomach changed markedly, showing prolongation in the second component,
potentiation in the spike component and depolarization in the membrane potential. These
results are direct effects of extracellular sodium on the smooth muscle cell membrane.
However, in low sodium concentration below about 10 mM, the influence of autonomic
nervous system on the slow wave becomes remarkable and above changes of the slow wave
cannot be found.