Increment of calcium-activated and delayed rectifier potassium current by hyposmotic swelling in gastric antral circular myocytes of guinea pig.
OBJECTIVE
To observe the effect of hyposmotic swelling on calcium-activated potassium current [IKCa] and delayed rectifier potassium current [IKV] in gastric antral circular myocytes of guinea pig.


METHODS
The whole cell patch-clamp technique was used, and the myocytes were isolated by collagenase. Cells were swelled by the hyposmotic solution (200 Osmmol/kg).


RESULTS
The hyposmotic solution markedly increased IKCa and IKV. The increase of IKCa was markedly inhibited by tetrathylammonium (TEA) 4 mmol/L and charybdotoxin (ChTX) 200 nmol/L. The increase of IKV was incompletely blocked by TEA and completely blocked by 4-aminopyridine (4-AP) 10 mmol/L. There was no significant difference between the amplitudes of the increase of IKCa and IKV (P < 0.05). IKCa increased (17.0 +/- 4.8) s after the cells were perfused with the hyposmotic solution, whereas IKV increased (30.7 +/- 13.7) s after the cells exposed to the hyposmotic solution. There was significant difference between the latency of IKCa and IKV (P < 0.05).


CONCLUSIONS
Hyposmotic swelling increased both IKCa and IKV, and the increment was likely related to the cell volume regulation.
Piao
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Research Laboratory of Digestive Physiology, College of Medicine, Yanbian University, Yanji 133000, China.
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D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D002469:Cell Separation; D018999:Charybdotoxin / Q000494:pharmacology; D051668:Delayed Rectifier Potassium Channels; D005260:Female; D006168:Guinea Pigs; D007038:Hypotonic Solutions / Q000494:pharmacology*; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors / Q000187:drug effects*; D024642:Potassium Channels, Voltage-Gated; D011706:Pyloric Antrum / Q000166:cytology / Q000502:physiology*
D051668:Delayed Rectifier Potassium Channels; D007038:Hypotonic Solutions; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D018999:Charybdotoxin; D015761:4-Aminopyridine