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. 1985 Dec;369:283–294. doi: 10.1113/jphysiol.1985.sp015901

Gradient in excitation-contraction coupling in canine gastric antral circular muscle.

A J Bauer, K M Sanders
PMCID: PMC1192649  PMID: 4093884

Abstract

Slow waves decay in amplitude as they propagate through the thickness of circular muscle of the canine antrum. Slow waves are the excitable events that initiate contractions in the antrum. Excitation-contraction coupling occurs if slow wave depolarizations surpass a 'mechanical threshold'. The amplitude of slow waves recorded from circular muscle cells near the submucosa was insufficient to reach the mechanical threshold previously determined for muscle near the myenteric plexus, suggesting that either submucosal cells are normally mechanically quiescent, or that contractions of submucosal cells are initiated at more polarized levels. Experiments were performed to determine the voltage-tension relationships in adjacent 'myenteric' and 'submucosal' circular muscles. Membrane potentials of the muscles were depolarized by elevated concentrations of potassium. Submucosal muscles were stimulated to contract at lower potassium concentrations than were myenteric muscles. Contractions of submucosal muscles at each potassium concentration studied were more forceful than contractions of myenteric muscles. Plots of membrane potential vs. potassium concentration on a logarithmic scale showed that the membrane potential of myenteric cells was more dependent upon the potassium gradient than the membrane potential of submucosal cells. The potassium permeability of both groups of cells increased when depolarized, and the slopes of these plots approached Nernstian levels when depolarized below -55 mV. Force developed in submucosal strips at more polarized levels than in myenteric muscles. The 'mechanical threshold' of submucosal muscles was 5-10 mV above resting potential, whereas myenteric muscles had to be depolarized by 25-30 mV before contraction was initiated. The mechanisms responsible for the difference in mechanical thresholds are not known, but differences in the voltage dependence of calcium channels, in calcium release mechanisms, or in the sensitivity of the contractile proteins to calcium could be involved.

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Selected References

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

  1. Bauer A. J., Reed J. B., Sanders K. M. Slow wave heterogeneity within the circular muscle of the canine gastric antrum. J Physiol. 1985 Sep;366:221–232. doi: 10.1113/jphysiol.1985.sp015793. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bortoff A., Michaels D., Mistretta P. Dominance of longitudinal muscle in propagation of intestinal slow waves. Am J Physiol. 1981 Mar;240(3):C135–C147. doi: 10.1152/ajpcell.1981.240.3.C135. [DOI] [PubMed] [Google Scholar]
  3. Bortoff A., Sachs F. Electrotonic spread of slow waves in circular muscle of small intestine. Am J Physiol. 1970 Feb;218(2):576–581. doi: 10.1152/ajplegacy.1970.218.2.576. [DOI] [PubMed] [Google Scholar]
  4. Coburn R. F., Yamaguchi T. Membrane potential-dependent and-independent tension in the canine tracheal muscle. J Pharmacol Exp Ther. 1977 May;201(2):276–284. [PubMed] [Google Scholar]
  5. Connor J. A., Kreulen D., Prosser C. L., Weigel R. Interaction between longitudinal and circular muscle in intestine of cat. J Physiol. 1977 Dec;273(3):665–689. doi: 10.1113/jphysiol.1977.sp012116. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Dillon P. F., Murphy R. A. High force development and crossbridge attachment in smooth muscle from swine carotid arteries. Circ Res. 1982 Jun;50(6):799–804. doi: 10.1161/01.res.50.6.799. [DOI] [PubMed] [Google Scholar]
  7. EDWARDS C., CHICHIBU S., HAGIWARA S. RELATION BETWEEN MEMBRANE POTENTIAL CHANGES AND TENSION IN BARNACLE MUSCLE FIBERS. J Gen Physiol. 1964 Nov;48:225–234. doi: 10.1085/jgp.48.2.225. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Farley J. M., Miles P. R. Role of depolarization in acetylcholine-induced contractions of dog trachealis muscle. J Pharmacol Exp Ther. 1977 Apr;201(1):199–205. [PubMed] [Google Scholar]
  9. HODGKIN A. L., HOROWICZ P. Potassium contractures in single muscle fibres. J Physiol. 1960 Sep;153:386–403. doi: 10.1113/jphysiol.1960.sp006541. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. HOYLE G., SMYTH T., Jr NEUROMUSCULAR PHYSIOLOGY OF GIANT MUSCLE FIBERS OF A BARNACLE, BALANUS NUBILUS DARWIN. Comp Biochem Physiol. 1963 Dec;10:291–314. doi: 10.1016/0010-406x(63)90229-9. [DOI] [PubMed] [Google Scholar]
  11. Hagiwara S., Takahashi K., Junge D. Excitation-contraction coupling in a barnacle muscle fiber as examined with voltage clamp technique. J Gen Physiol. 1968 Feb;51(2):157–175. doi: 10.1085/jgp.51.2.157. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Huddart H., Abram R. G. Modification of excitation-contraction coupling in locust skeletal muscle induced by caffeine. J Exp Zool. 1969 May;171(1):49–58. doi: 10.1002/jez.1401710108. [DOI] [PubMed] [Google Scholar]
  13. LEVVY G. A., McALLAN A. Some plant glycosidases. Nature. 1962 Jul 28;195:387–387. doi: 10.1038/195387a0. [DOI] [PubMed] [Google Scholar]
  14. Mishima K., Kuriyama H. Effects of prostaglandins on electrical and mechanical activities of the guinea pig stomach. Jpn J Physiol. 1976;26(5):537–548. doi: 10.2170/jjphysiol.26.537. [DOI] [PubMed] [Google Scholar]
  15. Morgan K. G., Schmalz P. F., Szurszewski J. H. The inhibitory effects of vasoactive intestinal polypeptide on the mechanical and electrical activity of canine antral smooth muscle. J Physiol. 1978 Sep;282:437–450. doi: 10.1113/jphysiol.1978.sp012474. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Morgan K. G., Szurszewski J. H. Mechanisms of phasic and tonic actions of pentagastrin on canine gastric smooth muscle. J Physiol. 1980 Apr;301:229–242. doi: 10.1113/jphysiol.1980.sp013201. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Sanders K. M. Endogenous prostaglandin E and contractile activity of isolated ileal smooth muscle. Am J Physiol. 1978 Feb;234(2):E209–E212. doi: 10.1152/ajpendo.1978.234.2.E209. [DOI] [PubMed] [Google Scholar]
  18. Washizu Y. Membrane potential and tension in guinea-pig ureter. J Pharmacol Exp Ther. 1967 Dec;158(3):445–450. [PubMed] [Google Scholar]
  19. el-Sharkawy T. Y., Szurszewski J. H. Modulation of canine antral circular smooth muscle by acetylcholine, noradrenaline and pentagastrin. J Physiol. 1978 Jun;279:309–320. doi: 10.1113/jphysiol.1978.sp012346. [DOI] [PMC free article] [PubMed] [Google Scholar]

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