Actin filament disruption inhibits L-type Ca(2+) channel current in cultured vascular smooth muscle cells

To clarify interactions between the cytoskeleton and activity of L-type Ca(2+) (Ca(L)) channels in vascular smooth muscle (VSM) cells, we investigated the effect of disruption of actin filaments and microtubules on the L-type Ca(2+) current [I(Ba(L))] of cultured VSM cells (A7r5 cell line) using who...

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Bibliographic Details
Published in:American Journal of Physiology: Cell Physiology 2000-08, Vol.279 (2), p.C480-C487
Main Authors: Nakamura, M, Sunagawa, M, Kosugi, T, Sperelakis, N
Format: Article
Language:English
Subjects:
Actins - drug effects
Actins - metabolism
Animals
Aorta - drug effects
Aorta - metabolism
Calcium Channels, L-Type - drug effects
Calcium Channels, L-Type - metabolism
Cells, Cultured
Colchicine - pharmacology
Cytochalasin D - pharmacology
Gout Suppressants - pharmacology
Microtubules - drug effects
Microtubules - metabolism
Muscle, Smooth, Vascular - drug effects
Muscle, Smooth, Vascular - metabolism
Nucleic Acid Synthesis Inhibitors - pharmacology
Rats
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Summary:To clarify interactions between the cytoskeleton and activity of L-type Ca(2+) (Ca(L)) channels in vascular smooth muscle (VSM) cells, we investigated the effect of disruption of actin filaments and microtubules on the L-type Ca(2+) current [I(Ba(L))] of cultured VSM cells (A7r5 cell line) using whole cell voltage clamp. The cells were exposed to each disrupter for 1 h and then examined electrophysiologically and morphologically. Results of immunostaining using anti-alpha-actin and anti-alpha-tubulin antibodies showed that colchicine disrupted both actin filaments and microtubules, cytochalasin D disrupted only actin filaments, and nocodazole disrupted only microtubules. I(Ba(L)) was greatly reduced in cells that were exposed to colchicine or cytochalasin D but not to nocodazole. Colchicine even inhibited I(Ba(L)) by about 40% when the actin filaments were stabilized by phalloidin or when the cells were treated with phalloidin plus taxol to stabilize both cytoskeletal components. These results suggest that colchicine must also cause some inhibition of I(Ba(L)) due to another unknown mechanism, e.g., a direct block of Ca(L) channels. In summary, actin filament disruption of VSM cells inhibits Ca(L) channel activity, whereas disrupting the microtubules does not.
ISSN:0363-6143
DOI:10.1152/ajpcell.2000.279.2.c480