Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Single K+ channels in membrane evaginations of smooth muscle cells

  • 23 Accesses

  • 31 Citations


Attempts have been made to apply the patch-clamp technique to enzymatically dispersed smooth muscle cells of frog and toad stomach. The rate of successful gigaseal formation has been extremely low, but better results can be obtained when patches are taken from membrane evaginations which develop on single cells after mechanical agitation and incubation in Ca2+-containing solutions at 25° C. Also ball-shaped single cells formed by the confluence of membrane evaginations were found to be equally useful for patch-clamp studies. Giga-seal formation was obtained in more than 80% of all attempts. Electron micrographs indicate that the myofilaments in membrane evaginations an in ball-shaped cells are separated from the cell membrane. Channel activity in membrane patches of such “myoballs” or evaginations is similar to the channel activity as found in intact cells. Two types of K+ channels (100 and 200 pS) have been observed that can be blocked by tetraethylammonium. Channels with the conductance of 200 pS are activated by intracellular Ca2+. The formation of evaginations has also been observed in other cells and may help to apply the patch-clamp technique to cells contaminated with surface coats.

This is a preview of subscription content, log in to check access.


  1. Bagby RM, Young AM, Dotson RK, Fisher BA, McKinnon K (1971) Contraction of single smooth muscle cells from Buffo marinus stomach. Nature 234:351–352

  2. Barth LG, Barth LJ (1959) Differentiation of cells of the Rana pipiens gastrula in unconditioned medium. J Embryol Exp Morphol 7:210–222

  3. Benham CD, Bolton TB (1983) Patch-clamp studies of slow potential-sensitive potassium channels in longitudinal smooth muscle cells of rabbit jejunum. J Physiol (Lond) 340:469–486

  4. Benham CD, Bolton TB, Lang RJ (1983) Patch-clamp studies of the action of K+-channel blockers on two types of K+ channels in dispersed smooth muscle cells of rabbit jejunum. J Physiol (Lond) 341:23p-24p

  5. Bemham CD, Bolton TB, Lang RJ, Takewaki T (1984) Calcium-dependent K+ channels in dispersed intestinal and arterial smooth muscle cells of guinea-pigs and rabbits studied by the patch-calmp technique. J Physiol (Lond) 350:53p

  6. Colquhoun D, Neher E, Reuter H, Stevens CF (1981) Inward current channels activated by intracellular Ca in cultured cardiac cells. Nature 294:752–754

  7. Fay SF, Delise CM (1973) Contraction of isolated smooth muscle cells — Structural changes. Proc Natl Acad Sci USA 70:641–645

  8. Gorman ALF, Hermann A, Thomas MV (1981) Intracellular calcium and the control of neural pacemaker activity. Fed Proc 40:2233–2239

  9. Grout BWW, Fuller BJ (1982) Hepatocyte plasma membrane response to hypertonic stress and related cell viability. Cryo Letters 3:51–56

  10. Grygorczyk R, Schwarz W (1984) Inhibition of Ca2+-activated K+ channels in human erythrocytes. Pflügers Arch 400:R 25 (Suppl)

  11. Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100

  12. Labarca PP, Miller C (1981) A K+-selective, three-state channel from fragmented sarcoplasmic reticulum of frog leg muscle. J Membrane Biol 61:31–38

  13. McLellan MR, Morris GJ, Kalinina LV (1982) Membrane evagination from Amoeba proteus in response to stress under isotonic conditions. Cryo-Letters 3:35–40

  14. Meech RW (1978) Calcium-dependent potassium activation in nervous tissues. Ann Rev Biophys Bioeng 7:1–18

  15. Schwarz W, Neumcke B, Palade PT (1981) K-current fluctuations in inward-rectifying channels of frog skeletal muscle. J Membrane Biol 63:85–92

  16. Singer JJ, Walsh JV (1982) Single-channel currents recorded in freshly dissociated vertebrate smooth muscle cells using the patch-clamp technique. J Gen Physiol 8:23a-24a

  17. Singer JJ, Walsh JV (1984) Large conductance Ca++-activated K+ channels in smooth muscle cell membrane: Reduction in unitary currents due to internal Na+ ions. Biophys J 45:68–70

  18. Stämpfli R, Westerheide G (1959) Die Verwendung eines Bündels aus der Ringmuskulatur des Forschmagens zur Untersuchung der Eigenschaften glatter Muskelfasern. Helv Physiol Acta 17:C 42

  19. Walsh JV, Singer JJ (1981) Voltage clamp of single freshly dissociated smooth muscle cells: Current-voltage relationships for three currents. Pflügers Arch 390:207–210

  20. Yellen G (1982) Singe Ca2+-activated non-selective cation channels in neuro-blastoma. Nature 296:357–359

  21. Zollinger UH (1948) Cytological studies with the phase microscope. I. The formation of “blisters” on cells in suspension (Potocytosis), with observations on the nature of the cellular membrane. Am J Pathol 24:545–558

Download references

Author information

Correspondence to W. Schwarz.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Berger, W., Grygorcyk, R. & Schwarz, W. Single K+ channels in membrane evaginations of smooth muscle cells. Pflugers Arch. 402, 18–23 (1984). https://doi.org/10.1007/BF00584826

Download citation

Key words

  • Single smooth muscle cell
  • Patch clamp
  • Potassium channel
  • Membrane evagination