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Updated: Oct 1, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
Published on: July 3, 2013
Effects of K(ATP) channel modulators on acetylcholine release from guinea-pig isolated atria and small intestine
H Kilbinger1, A Krause, C F Mang
1Pharmakologisches Institut, Universität Mainz, 55101 Mainz, Germany. KILBINGE@mail.uni-mainz.de
Abstract:
The effects of K(ATP) channel blockers (glibenclamide, HMR 1883, HMR 1372) and openers (cromakalim, pinacidil, diazoxide) on the electrically-evoked (5 Hz) release of [(3)H]acetylcholine were studied in isolated guinea-pig atria and myenteric plexus-longitudinal muscle preparations which had been preincubated with [(3)H]choline. Atria: Cromakalim (0.3 microM and 1 microM), pinacidil (10 microM) and diazoxide (30 microM) significantly reduced the stimulation-evoked release of [(3)H]acetylcholine. The inhibition produced by cromakalim and pinacidil was prevented by 1 microM of either HMR 1883, HMR 1372 or glibenclamide. The blockers alone significantly increased the release at concentrations of 30 microM, whereas 1 microM and 10 microM had no effect. Myenteric plexus-longitudinal muscle preparation: The electrically-evoked release of [(3)H]acetylcholine was not affected by K(ATP) channel blockers or openers. In contrast, the contractions of the longitudinal muscle caused by electrical stimulation or by carbachol were strongly inhibited by 1 microM cromakalim which suggests that the relaxant effect of the K(ATP) channel openers is exclusively a direct effect on intestinal smooth muscle. The findings suggest that blockade of activated K(ATP) channels in vagal nerves of guinea-pig atria stimulates acetylcholine release, and that this effect may contribute to the antiarrhythmic actions of K(ATP) channel blockers. By contrast, release of acetylcholine from guinea-pig myenteric plexus is not modulated by K(ATP) channels which suggests heterogeneity of K(ATP) channel distribution in peripheral autonomic nerves.
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