Abstract
The effects of heparin on activation of the G protein-gated muscarinic K+ channel were examined in atrial cells of guinea-pig heart. The inside-out patch clamp technique was used. The pipette solution contained 1.1 μM acetylcholine (ACh). In the inside-out patches, intracellular GTP activated the muscarinic K+ channel. When heparin (0.05–5 units/ml) was further added to the intracellular side of the patch membrane, the channel openings were depressed in a concentration-dependent fashion. The effects of heparin were reversible after wash-out. Heparin did not affect GTP-γS-induced activation of the K+ channel. Therefore, it is suggested that heparin may uncouple the muscarinic receptors from GK protein in the cardiac atrial cell membrane.
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Ito, H., Takikawa, R., Iguchi, M. et al. Heparin uncouples the muscarinic receptors from GK protein in the atrial cell membrane of the guinea-pig heart. Pflugers Arch. 417, 126–128 (1990). https://doi.org/10.1007/BF00370783
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DOI: https://doi.org/10.1007/BF00370783