Pflügers Archiv

, Volume 446, Issue 5, pp 523–528

Actin filaments regulate the stretch sensitivity of large-conductance, Ca2+-activated K+ channels in coronary artery smooth muscle cells

Cardiovascular System


Using the inside-out patch-clamp technique, large-conductance Ca2+-activated K+ channel (BKCa) currents were recorded from coronary artery smooth muscle cells. Cytochalasin D, an actin filament disrupter, increased channel activity (NPo, where N is the number of channels and Po the open probability), and this increase was reversed by phalloidin, an actin filament stabilizer. NPo was also increased by colchicine, a microtubule disrupter, and decreased by taxol, a microtubule stabilizer. With the stepwise increase of negative pressure in the patch pipettes, the activity of BKCa gradually increased: the maximum effect (527% increase in NPo) was achieved at −40 cmH2O and the half-maximum effect at −25 cmH2O. The increase in NPo in response to negative pressure was abolished by phalloidin but not by taxol. These results imply that both actin filaments and microtubules inhibit the opening of BKCa in coronary artery smooth muscle cells, but that only actin filaments are involved in the stretch sensitivity of BKCa.


Vascular smooth muscle Ca2+-activated K+ channel Membrane stretch Cytoskeleton Actin filaments Microtubules 


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Copyright information

© Springer-Verlag  2003

Authors and Affiliations

  1. 1.National Research Laboratory for Cellular Signalling and Department of PhysiologySeoul National University College of MedicineSeoulKorea

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