Role of actin microfilament in osmotic stretch-induced increase of voltage-operated calcium channel current in guinea-pig gastric myocytes.
Using the whole-cell patch clamp technique, the role of actin microfilament in hyposmotic increase of voltage-operated calcium channel current (IBa) was studied in guinea-pig gastric myocytes. Hyposmotic superfusate (212 mOsm) increased peak IBa amplitude by 32.7 +/- 6.5%; when cytochalasin-D (Cyt-D, 20 microM), an actin cytoskeleton disruptor, was used, an increase of only 9.7 +/- 3.1% was seen. IBa response to osmotic stress was potentiated (45.1 +/- 4.1% increase) by 20 microM phalloidin, an actin microfilament stabilizer. However, colchicine (100 microM), an microtubule cytoskeleton disruptor, had no effect on either IBa or its response to hyposmotic solution. Phalloidin also induced a rightward shift of the I/V relationship of IBa, while Cyt-D itself had no effect. These results suggest that actin cytoskeleton may mediate hyposmotic stretch-induced IBa increase in gastric smooth muscle.
Xu
W X
WX
Department of Physiology and Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea.
Kim
S J
SJ
So
I
I
Kim
K W
KW
D008841:Actin Cytoskeleton / Q000502:physiology*; D000199:Actins / Q000502:physiology*; D000818:Animals; D015220:Calcium Channels / Q000502:physiology*; D003078:Colchicine / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D004594:Electrophysiology; D006168:Guinea Pigs; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009995:Osmosis; D018408:Patch-Clamp Techniques; D010590:Phalloidine / Q000494:pharmacology; D013270:Stomach / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013314:Stress, Mechanical
D000199:Actins; D015220:Calcium Channels; D010590:Phalloidine; D015638:Cytochalasin D; D003078:Colchicine