Coupling of a P2Z-like purinoceptor to a fatty acid-activated K(+) channel in toad gastric smooth muscle cells
Department of Physiology
Adenosine Triphosphate; Animals; Bufo marinus; Calcium; Cell Membrane; Electric Conductivity; Electrophysiology; Extracellular Space; Fatty Acids; GTP-Binding Proteins; Intracellular Fluid; Muscle, Smooth; Osmolar Concentration; Patch-Clamp Techniques; Potassium Channels; Receptors, Purinergic P2; Stomach
Life Sciences | Medicine and Health Sciences
1. Extracellular application of ATP generates two whole-cell currents in toad gastric smooth muscle cells: an immediate inward non-selective cation current (due to the activation of a P2X or P2Z-like receptor) and a slowly developing outward K(+) current. The inward non-selective cation current depends on the continuous presence of ATP while the outward K(+) current can last for minutes after ATP application ceases. 2. In cell-attached patches, application of ATP to the extra-patch membrane can activate K(+) channels in the patch indicating that a diffusible cellular messenger may be involved. The characteristics of these K(+) channels are similar to those of a previously described fatty acid-activated K(+) channel that is also a stretch-activated channel. 3. This whole-cell K(+) current can be induced by ATP in the absence of extracellular Ca(2+) (with EGTA present to chelate trace amounts). However, the current generated in the presence of extracellular Ca(2+) is considerably larger. 4. The pharmacological profiles for the activation of the non-selective cation current and the K(+) current are similar, suggesting that the same P2Z-like receptor could be mediating both responses. This type of plasma membrane receptor/channel-channel coupling by a process that does not appear to involve Ca(2+) flow through the receptor/channel or a subsequent membrane potential change may be representative of a new class of signalling mechanisms.
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Citation: J Physiol. 2001 Jul 1;534(Pt 1):59-70.
The Journal of physiology
Zou, Hui; Ugur, Mehmet; Drummond, Robert M.; and Singer, Joshua J., "Coupling of a P2Z-like purinoceptor to a fatty acid-activated K(+) channel in toad gastric smooth muscle cells" (2001). Open Access Articles. 1488.