Effect of cytochalasin B on intestinal smooth muscle cells.
The inhibitory effect of cytochalasin B on contraction of smooth muscle cells isolated from guinea-pig taenia coli was investigated. Cytochalasin B (10-70 microM) inhibited the high K+ (70 mM)-induced contraction in a dose-dependent manner, and the maximum and the half-maximum effects were obtained at 50 and 15 microM, respectively. Cytochalasin B (70 microM) decreased ATPase activity in skinned guinea-pig taenia coli. However, cytochalasin B (50 microM) had no significant effect on the voltage-dependent Ca2+ currents, the passive membrane properties or the membrane potential. Cytochalasin B also had no effect on the phosphorylation of 20 kDa myosin light chain induced by high K+ and cytosolic Ca2+ levels. These results suggest that the inhibition of contraction by cytochalasin B may be due to its effects on actin of microfilaments and contractile filaments of guinea-pig taenia coli smooth muscle cells.
Obara
K
K
Department of Physiology, School of Medicine, Sapporo Medical University, Japan.
Yabu
H
H
D000199:Actins / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D003571:Cytochalasin B / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008566:Membranes / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015879:Myosin Subfragments / Q000378:metabolism; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology
D000199:Actins; D015220:Calcium Channels; D015879:Myosin Subfragments; D003571:Cytochalasin B; D000251:Adenosine Triphosphatases; D011188:Potassium