Cyclic GMP-induced activation of potassium currents by sarcoplasmic reticulum Ca2+ pump-dependent mechanism

D. B. Duridanova, H. S. Gagov, Georgi Petkov, G. B. Shkodrov, K. K. Boev

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

In voltage-clamped single smooth muscle cells from the circular layer of the guinea-pig gastric fundus NO-liberating substance or an analogue of cyclic 3',5'-guanosine monophosphate (cGMP) increased or decreased the outward NK+ current amplitudes depending on the Ca2+ buffering capacity of the intracellular medium. In a high EGTA-containing pipette solution dibutyryl-cGMP or sodium nitroprusside (SNP) attenuated both the fast and the late K+ current components. In pipette solution with lower Ca2+-buffering capacity these drugs caused a sustained increase of K+ current amplitudes, which was effectively antagonized by thapsigargin, an inhibitor of Ca2+-ATPase in the sarcoplasmic reticulum (SR). Our data suggest that, in gastric fundus smooth muscles, NO-liberating substances and cGMP analogues contribute to the activation of a Ca2+-release mechanism from the cell bulk, i.e. the myoplasm surrounding the contractile filaments, towards the plasma membrane, crossing the SR Ca2+-stores. Thus, a decreased intracellular free calcium concentration ([Ca2+]) is coupled with an elevation of subplasmalemmal calcium, which in turn causes cell membrane hyperpolarization. The latter is a consequence of the opening of tetraethylammonium-sensitive Ca2+-activated K+ channels and leads to sustained smooth muscle relaxation, most characteristic for gastric fundus preparations.

Original languageEnglish (US)
Pages (from-to)139-151
Number of pages13
JournalGeneral Physiology and Biophysics
Volume14
Issue number2
StatePublished - Sep 1 1995
Externally publishedYes

Fingerprint

Gastric Fundus
Cyclic GMP
Sarcoplasmic Reticulum
Potassium
Smooth Muscle
Dibutyryl Cyclic GMP
Cell Membrane
Calcium
Calcium-Activated Potassium Channels
Tetraethylammonium
Muscle Relaxation
Thapsigargin
Calcium-Transporting ATPases
Egtazic Acid
Nitroprusside
Smooth Muscle Myocytes
Guinea Pigs
Pharmaceutical Preparations

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Medicine(all)
  • Physiology

Cite this

Cyclic GMP-induced activation of potassium currents by sarcoplasmic reticulum Ca2+ pump-dependent mechanism. / Duridanova, D. B.; Gagov, H. S.; Petkov, Georgi; Shkodrov, G. B.; Boev, K. K.

In: General Physiology and Biophysics, Vol. 14, No. 2, 01.09.1995, p. 139-151.

Research output: Contribution to journalArticle

Duridanova, D. B. ; Gagov, H. S. ; Petkov, Georgi ; Shkodrov, G. B. ; Boev, K. K. / Cyclic GMP-induced activation of potassium currents by sarcoplasmic reticulum Ca2+ pump-dependent mechanism. In: General Physiology and Biophysics. 1995 ; Vol. 14, No. 2. pp. 139-151.
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