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. 1993 Jul;466:213–227.

Properties of stretch-activated channels in myocytes from the guinea-pig urinary bladder.

M C Wellner 1, G Isenberg 1
PMCID: PMC1175475  PMID: 7692040

Abstract

1. Stretch-activated channels (SACs) were analysed on patches attached to myocytes isolated from the guinea-pig urinary bladder. At 22 degrees C application of -2 to -4 kPa to the patch electrode induced SACs at a density of one to two per patch (3-5 M omega electrodes). 2. With electrodes containing 145 mM K+, 20 mM TEA and 2 mM Mg2+, the single channel current followed a linear I-V curve with a slope conductance of 39 +/- 5 pS (mean +/- S.D.) and a reversal potential of 2 +/- 6 mV. Substitution of chloride by aspartate ions left both parameters unchanged suggesting that the anions do not contribute to the currents. 3. Hyperpolarization from -30 to -80 mV did not open channels by itself but increased channel activity (NPo; where N is the number of channels in the patch and Po is the probability of the channel being open) twofold. The hyperpolarization-induced increase in NPo can be attributed to a reduction of long closures. At positive patch potentials numerous blank records strongly diminished NPo. 4. Inward currents through SACs can be carried by a variety of cations. In the presence of 2 mM Mg2+, the respective channel conductance was 40 +/- 4 pS for 140 mM K+ > 34 +/- 2 pS for 140 mM Na+ > or = 33 +/- 6 pS for 140 mM Cs+ > 19 +/- 2 pS for 110 mM Ba2+ > 17 +/- 2 pS for 110 mM Ca2+. 5. Reduction of CaCl2 from 110 to 10 mM did not change the conductance but shifted the reversal potential from +7 to -7 mV; the reversal potentials suggest that SACs are slightly more permeable for Ca2+ than for K+. 6. In the absence of divalent cations, the conductance of K+ was 82 +/- 4 pS for inward but 45 pS for outward currents. Addition of either 2 mM Ca2+ or 2 mM Mg2+ reduced the conductance for inward currents to 40 pS. 7. The change from 140 to 14 mM KCl plus 136 mM Tris-Cl reduced the conductance from 82 to 56 pS whereas the reversal potential shifted only from -4 to -9 mV. When 20 mM K+ and 300 mM sucrose were applied, the conductance fell to 39 pS and the reversal potential shifted by -30 mV. The results suggest that Tris+ can permeate through SACs when extracellular divalent cations are absent.(ABSTRACT TRUNCATED AT 400 WORDS)

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Selected References

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

  1. Bear C. E. A nonselective cation channel in rat liver cells is activated by membrane stretch. Am J Physiol. 1990 Mar;258(3 Pt 1):C421–C428. doi: 10.1152/ajpcell.1990.258.3.C421. [DOI] [PubMed] [Google Scholar]
  2. Benham C. D., Bolton T. B., Denbigh J. S., Lang R. J. Inward rectification in freshly isolated single smooth muscle cells of the rabbit jejunum. J Physiol. 1987 Feb;383:461–476. doi: 10.1113/jphysiol.1987.sp016421. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cooper K. E., Tang J. M., Rae J. L., Eisenberg R. S. A cation channel in frog lens epithelia responsive to pressure and calcium. J Membr Biol. 1986;93(3):259–269. doi: 10.1007/BF01871180. [DOI] [PubMed] [Google Scholar]
  4. Creed K. E. Membrane properties of the smooth muscle membrane of the guinea-pig urinary bladder. Pflugers Arch. 1971;326(2):115–126. doi: 10.1007/BF00586904. [DOI] [PubMed] [Google Scholar]
  5. Davis M. J., Donovitz J. A., Hood J. D. Stretch-activated single-channel and whole cell currents in vascular smooth muscle cells. Am J Physiol. 1992 Apr;262(4 Pt 1):C1083–C1088. doi: 10.1152/ajpcell.1992.262.4.C1083. [DOI] [PubMed] [Google Scholar]
  6. Guharay F., Sachs F. Stretch-activated single ion channel currents in tissue-cultured embryonic chick skeletal muscle. J Physiol. 1984 Jul;352:685–701. doi: 10.1113/jphysiol.1984.sp015317. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Hess P., Lansman J. B., Tsien R. W. Calcium channel selectivity for divalent and monovalent cations. Voltage and concentration dependence of single channel current in ventricular heart cells. J Gen Physiol. 1986 Sep;88(3):293–319. doi: 10.1085/jgp.88.3.293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Hisada T., Ordway R. W., Kirber M. T., Singer J. J., Walsh J. V., Jr Hyperpolarization-activated cationic channels in smooth muscle cells are stretch sensitive. Pflugers Arch. 1991 Jan;417(5):493–499. doi: 10.1007/BF00370945. [DOI] [PubMed] [Google Scholar]
  9. Isenberg G., Klockner U. Calcium tolerant ventricular myocytes prepared by preincubation in a "KB medium". Pflugers Arch. 1982 Oct;395(1):6–18. doi: 10.1007/BF00584963. [DOI] [PubMed] [Google Scholar]
  10. Kirber M. T., Walsh J. V., Jr, Singer J. J. Stretch-activated ion channels in smooth muscle: a mechanism for the initiation of stretch-induced contraction. Pflugers Arch. 1988 Sep;412(4):339–345. doi: 10.1007/BF01907549. [DOI] [PubMed] [Google Scholar]
  11. Klöckner U., Isenberg G. Action potentials and net membrane currents of isolated smooth muscle cells (urinary bladder of the guinea-pig). Pflugers Arch. 1985 Dec;405(4):329–339. doi: 10.1007/BF00595685. [DOI] [PubMed] [Google Scholar]
  12. Klöckner U., Isenberg G. Calcium currents of cesium loaded isolated smooth muscle cells (urinary bladder of the guinea pig). Pflugers Arch. 1985 Dec;405(4):340–348. doi: 10.1007/BF00595686. [DOI] [PubMed] [Google Scholar]
  13. Markwardt F., Isenberg G. Gating of maxi K+ channels studied by Ca2+ concentration jumps in excised inside-out multi-channel patches (myocytes from guinea pig urinary bladder). J Gen Physiol. 1992 Jun;99(6):841–862. doi: 10.1085/jgp.99.6.841. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Sokabe M., Sachs F., Jing Z. Q. Quantitative video microscopy of patch clamped membranes stress, strain, capacitance, and stretch channel activation. Biophys J. 1991 Mar;59(3):722–728. doi: 10.1016/S0006-3495(91)82285-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Taglietti V., Toselli M. A study of stretch-activated channels in the membrane of frog oocytes: interactions with Ca2+ ions. J Physiol. 1988 Dec;407:311–328. doi: 10.1113/jphysiol.1988.sp017417. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Ubl J., Murer H., Kolb H. A. Ion channels activated by osmotic and mechanical stress in membranes of opossum kidney cells. J Membr Biol. 1988 Sep;104(3):223–232. doi: 10.1007/BF01872324. [DOI] [PubMed] [Google Scholar]
  17. Yang X. C., Sachs F. Block of stretch-activated ion channels in Xenopus oocytes by gadolinium and calcium ions. Science. 1989 Feb 24;243(4894 Pt 1):1068–1071. doi: 10.1126/science.2466333. [DOI] [PubMed] [Google Scholar]
  18. Yang X. C., Sachs F. Characterization of stretch-activated ion channels in Xenopus oocytes. J Physiol. 1990 Dec;431:103–122. doi: 10.1113/jphysiol.1990.sp018322. [DOI] [PMC free article] [PubMed] [Google Scholar]

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