Effect of actin microfilament on potassium current in guinea pig gastric myocytes.
OBJECTIVE
To investigate the effect of actin microfilament on potassium current and hyposmotic membrane stretch-induced increase of potassium current in gastric antral circular myocytes of guinea pig.


METHODS
Whole-cell patch clamp technique was used to record potassium current in isolated gastric myocyes.


RESULTS
When the membrane potential was clamped at -60 mV, an actin microfilament disruptor, cytochanlasin-B(Cyt-B, 20 micromol/L in pipette) increased calcium-activated potassium current (I(K(Ca))) and delayed rectifier potassium current (I(K(V))) to 138.4+/-14.3% and 142.1+/-13.1% respectively at +60 mV. In the same condition, an actin microfilament stabilizer phalloidin (20 micromol/L in pipette) inhibited I(K(Ca)) and I(K(V)) to 74.2+/-7.1% and 75.4+/-9.9% respectively. At the holding potential of -60 mV, hyposmotic membrane stretch increased I(K(Ca)) and I(K(V)) by 50.6+/-9.7% and 24.9+/-3.3% at +60 mV respectively. In the presence of cytochalasin-B and phalloidin (20 micromol/L, in the pipette) condition, hyposmotic membrane stretch also increased I(K(Ca)) by 44.5+/-7.9% and 55.7+/-9.8% at +60 mV respectively. In the same condition, cytochalasin-B and phalloidin also increased I(K(V)) by 23.0+/-5.5% and 30.3+/-4.5% respectively. However, Cyt-B and phalloidin did not affect the amplitude of hyposmotic membrane stretch-induced increase of I(K(Ca)) and I(K(V)).


CONCLUSIONS
Actin microfilaments regulate the activities of potassium channels, but they are not involved in the process of hyposmotic membrane stretch-induced increase of potassium currents in gastric antral circular myocytes of guinea pig.
Department of Physiology, Yanbian University College of Medicine, Yanji, Jilin Province, China.
Xiang-Lan
XL
Li
Hai-Feng
HF
Zheng
Zheng-Yuan
ZY
Jin
Meng
M
Yang
Zai-Liu
ZL
Li
Wen-Xie
WX
Xu
D008841:Actin Cytoskeleton / Q000502:physiology*; D000818:Animals; D003571:Cytochalasin B / Q000494:pharmacology; D006168:Guinea Pigs; D008564:Membrane Potentials / Q000187:drug effects; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D009997:Osmotic Pressure; D018408:Patch-Clamp Techniques; D010590:Phalloidine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000502:physiology*; D011706:Pyloric Antrum / Q000166:cytology*
D015221:Potassium Channels; D010590:Phalloidine; D003571:Cytochalasin B; D011188:Potassium