Effect of nitric oxide on calcium-activated potassium channels in colonie smooth muscle of rabbits

L. U. Gang, Bruno Mazet, Michael G. Sarr, Joseph H. Szurszewski

Research output: Contribution to journalArticle

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Abstract

Nitric oxide (NO) hvneruolarizes intestinal smooth muscle cells. This study was designed to determine the mechanism whereby NO activates Kca channels of circular smooth muscle of the rabbit colon. Transmural biopsies of the rabbit colon were stained for NADPH-diaphorase. Freshly dispersed circular smooth muscle cells were studied in the whole cell configuration, as well as in on-cell and excised inside-out patch recording configurations, while Kca current and the activity of Kca channels, respectively, were monitored. NADPH-diaphorase-positive nerve fibers were found in both muscle layers. NO (1%) increased whole cell net outward current by 79% and hyperpolarized resting membrane voltage from -59 to -73 mV (n = 8 cells, P < 0.01). In the on-cell patch recording configuration, NO (0.5% or 1%) in the bath increased NP0 of Kca channels; charybdotoxin (125 nM) in the pipette solution blocked this effect. In the excised inside-out patch recording configuration, NO (1%) had no effect on NP0 of Kca channels. In the on-cell patch recording configuration, méthylène blue (1 -M) or cystamine (5 mM) in the bath solution decreased the effect of NO (1%) on NP0 of Kca channels. NP0 was increased by 8-bromo-cGMP (8-BrcGMP; 1 mM), a cGMP analog, and zaprinast (100 //M), an inhibitor of cGMP phosphodiesterase. These data suggest that NO increased whole cell outward K+ current by activating Kca channels through a cGMP pathway. guanosine 3′,5′-cyclic monophosphate; NADPH.

Original languageEnglish (US)
JournalAmerican Journal of Physiology
Volume274
Issue number5 PART1
StatePublished - 1998

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Calcium-Activated Potassium Channels
Smooth Muscle
Nitric Oxide
Rabbits
NADPH Dehydrogenase
Baths
Smooth Muscle Myocytes
Colon
Cystamine
Charybdotoxin
Phosphodiesterase Inhibitors
Guanosine
NADP
Nerve Fibers
Biopsy
Muscles
Membranes

Keywords

  • Diaphorase
  • Dispersed smooth muscle cells

ASJC Scopus subject areas

  • Physiology (medical)

Cite this

Effect of nitric oxide on calcium-activated potassium channels in colonie smooth muscle of rabbits. / Gang, L. U.; Mazet, Bruno; Sarr, Michael G.; Szurszewski, Joseph H.

In: American Journal of Physiology, Vol. 274, No. 5 PART1, 1998.

Research output: Contribution to journalArticle

Gang, L. U. ; Mazet, Bruno ; Sarr, Michael G. ; Szurszewski, Joseph H. / Effect of nitric oxide on calcium-activated potassium channels in colonie smooth muscle of rabbits. In: American Journal of Physiology. 1998 ; Vol. 274, No. 5 PART1.
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