Involvement of actin cytoskeleton in modulation of apical K channel activity in rat collecting duct.
We have employed the patch-clamp technique to investigate the role of the actin cytoskeleton in the modulation of the low-conductance K+ channel in the apical membrane of the rat cortical collecting duct (CCD). This K+ channel is inactivated by application of cytochalasin B or D, both compounds known to disrupt actin filaments. The effect of both cytochalasins, B and D, was fully reversible in cell-attached patches, but channel activity could not be fully restored in excised membrane patches. The effect of cytochalasins on channel activity was specific and resulted from depolymerization of the actin cytoskeleton, since application of 10 microM chaetoglobosin C, a cytochalasin analogue that does not depolymerize the actin filaments, had no effect on channel activity in inside-out patches. Addition of either actin monomers or of the polymerizing actin filaments in inside-out patches to the cytosolic medium had no effect on channel activity. This suggests that cytochalasin B- or D-induced inactivation of apical K+ channels is not caused by obstruction of the channel pore by actin. We also observed that channel inhibition by cytochalasin B or D could be blocked by pretreatment with 5 microM phalloidin, a compound that stabilizes actin filaments. We conclude that apical K+ channel activity depends critically on the integrity of the actin cytoskeleton.
Wang
W H
WH
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Cassola
A
A
Giebisch
G
G
D000199:Actins / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D018613:Microscopy, Confocal; D010590:Phalloidine / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D000199:Actins; D015221:Potassium Channels; D010590:Phalloidine; D015638:Cytochalasin D; D003571:Cytochalasin B; D017868:Cyclic AMP-Dependent Protein Kinases