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. 1980 Feb;299:127–144. doi: 10.1113/jphysiol.1980.sp013115

Specific features of smooth muscle cells recorded from the placental region of the myometrium of pregnant rats

S Kanda 1, H Kuriyama 1
PMCID: PMC1279215  PMID: 7381762

Abstract

The muscle membrane and contractile properties of placental and non-placental regions of pregnant and postpartum myometria of the rat were investigated.

1. The membrane potential of the myometrium varied during the progress of gestation, but the membrane potential in the placental region was consistently higher than that in the non-placental region up to the last stage of gestation. The maximum difference in the membrane potential recorded from both regions was observed at 17-21 days gestation.

2. The conduction velocity of the excitation measured from muscle cells of the non-placental region was consistently larger than that of the placental region at any stage of the gestation (7-22 days). At 7 days gestation, the conduction velocity in the placental region could not be measured due to widely scattered values of the latencies for the spike generation. During the progress of gestation, the conduction velocity increased, and the value was consistently larger (about 10 times) in the nonplacental region than that in the placental region at any stage of gestation up to the last stage.

3. The length constant of the tissue measured from the non-placental region was larger (2·3 mm) than that in the placental region (1·1 mm) at 14 days gestation. The propagation of the excitation seems to be blocked from the cells of the non-placental region to the placental region, but not vice versa.

4. The shape of the spike in the non-placental region changed markedly during the progress of gestation. The spike could be recorded from the cells of the placental region but not consistently. However, the electrical activity of muscle cells recorded at the full term was much the same in both regions.

5. Various concentrations of [K]o or [Na]o modified the membrane potential. The differences in the membrane response to the above ionic environments appeared more significantly at the different stages of gestation, rather than topical differences.

6. Sensitivity of the muscle cell membrane to oxytocin in the placental region was higher than that in the non-placental region at any stage of gestation, while that to prostaglandin F2α was much the same in the cells recorded from both regions.

7. At 8 days gestation, the circular muscle layer is lost from the area of implantation and only the longitudinal muscle layer remains. The width of the placenta and the thickness of the muscle layer increased during the progress of gestation.

8. From the above results, the role of smooth muscle cells in the placental region is discussed in relation to hormonal controls in the myometrium, i.e. the activity of the muscle cell membrane in the placental region was markedly suppressed up to the last stage of gestation, however, there was no apparent direct relation between the inhibitory responses and the actions of progesterone.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Abe Y., Tomita T. Cable properties of smooth muscle. J Physiol. 1968 May;196(1):87–100. doi: 10.1113/jphysiol.1968.sp008496. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Akera T., Brody T. M. The role of Na+,K+-ATPase in the inotropic action of digitalis. Pharmacol Rev. 1977 Sep;29(3):187–220. [PubMed] [Google Scholar]
  3. BULBRING E., KURIYAMA H. Effects of changes in ionic environment on the action of acetylcholine and adrenaline on the smooth muscle cells of guinea-pig taenia coli. J Physiol. 1963 Apr;166:59–74. doi: 10.1113/jphysiol.1963.sp007090. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. BULBRING E., KURIYAMA H. Effects of changes in the external sodium and calcium concentrations on spontaneous electrical activity in smooth muscle of guinea-pig taenia coli. J Physiol. 1963 Apr;166:29–58. doi: 10.1113/jphysiol.1963.sp007089. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. CASTEELS R., KURIYAMA H. MEMBRANE POTENTIAL AND IONIC CONTENT IN PREGNANT AND NON-PREGNANT RAT MYOMETRIUM. J Physiol. 1965 Mar;177:263–287. doi: 10.1113/jphysiol.1965.sp007591. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. CSAPO A. Progesterone block. Am J Anat. 1956 Mar;98(2):273–291. doi: 10.1002/aja.1000980206. [DOI] [PubMed] [Google Scholar]
  7. DANIEL E. E., RENNER S. A. Effect of the placenta on the electrical activity of the cat uterus in vivo and in vitro. Am J Obstet Gynecol. 1960 Aug;80:229–244. doi: 10.1016/0002-9378(60)90118-6. [DOI] [PubMed] [Google Scholar]
  8. GOTO M., CSAPO A. The effect of the ovarian steroids on the membrane potential of uterine muscle. J Gen Physiol. 1959 Nov;43:455–466. doi: 10.1085/jgp.43.2.455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Ito Y., Suzuki H., Kuriyama H. Effects of sodium nitroprusside on smooth muscle cells of rabbit pulmonary artery and portal vein. J Pharmacol Exp Ther. 1978 Dec;207(3):1022–1031. [PubMed] [Google Scholar]
  10. KURIYAMA H., CSAPO A. Placenta and myometrial block. Am J Obstet Gynecol. 1961 Sep;82:592–599. doi: 10.1016/0002-9378(61)90277-0. [DOI] [PubMed] [Google Scholar]
  11. Kawarabayashi T. The effects of phenylephrine in various ionic environments on the circular muscle of mid-pregnant rat myometrium. Jpn J Physiol. 1978;28(5):627–645. doi: 10.2170/jjphysiol.28.627. [DOI] [PubMed] [Google Scholar]
  12. Kuriyama H., Suzuki H. Changes in electrical properties of rat myometrium during gestation and following hormonal treatments. J Physiol. 1976 Sep;260(2):315–333. doi: 10.1113/jphysiol.1976.sp011517. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Kuriyama H., Suzuki H. Effects of prostaglandin E2 and oxytocin on the electrical activity of hormone-treated and pregnant rat myometria. J Physiol. 1976 Sep;260(2):335–349. doi: 10.1113/jphysiol.1976.sp011518. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. MARSHALL J. M. Regulation of activity in uterine smooth muscle. Physiol Rev Suppl. 1962 Jul;5:213–227. [PubMed] [Google Scholar]
  15. Marshall J. M. Adrenergic innervation of the female reproductive tract: anatomy, physiology and pharmacology. Ergeb Physiol. 1970;62:6–67. doi: 10.1007/BFb0111421. [DOI] [PubMed] [Google Scholar]
  16. Osa T. An interaction between the electrical activities of longitudinal and circular smooth muscles of pregnant mouse uterus. Jpn J Physiol. 1974 Apr;24(2):189–203. doi: 10.2170/jjphysiol.24.189. [DOI] [PubMed] [Google Scholar]
  17. Osa T., Kawarabayashi T. Effect of ions and drugs on the plateau potential in the circular muscle of pregnant rat myometrium. Jpn J Physiol. 1977;27(1):111–121. doi: 10.2170/jjphysiol.27.111. [DOI] [PubMed] [Google Scholar]
  18. Osa T., Kuriyama H. Electrophysiological and mechanical investigations on the dual action of prostaglandin E1 in the pregnant rat myometrium in vitro. Jpn J Physiol. 1975;25(3):357–369. doi: 10.2170/jjphysiol.25.357. [DOI] [PubMed] [Google Scholar]
  19. Osa T. The effects of sodium, calcium and manganese on the electrical and mechanical activities of the myometrial smooth muscle of pregnant mice. Jpn J Physiol. 1973 Apr;23(2):113–133. doi: 10.2170/jjphysiol.23.113. [DOI] [PubMed] [Google Scholar]
  20. Suzuki H., Kuriyama H. Effects of prostaglandin E2 on the electrical property of the pregnant mouse myometrium. Jpn J Physiol. 1975;25(2):201–215. doi: 10.2170/jjphysiol.25.201. [DOI] [PubMed] [Google Scholar]

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