Regulation of swelling-activated chloride channels in embryonic chick heart cells

Abstract

Swelling-activated Cl − currents, I (Cl,swell) , were measured during hyposmotic shock in white Leghorn embryonic chick heart cells using the whole-cell recording of patch-clamp technique. Genistein, an inhibitor of protein tyrosine kinase (PTK), suppressed I (Cl,swell) . Under isosmotic condition phorbol 12-myristate 13-acetate (PMA), an activator of PKC, elicited the Cl − current similar to that in hyposmotic solution, whereas hyposmotic shock did not elicit I (Cl,swell) in chelerythrine chloride(an inhibitor of PKC)-treated cells. Confocal microscopy experiments using FITC-phalloidin as a fluorescent label of F-actin showed that the actin network was moved from cortical region of the cell to the center after hyposmotic shock as compared with the image under isosmotic condition. When the cells were treated with cytochalasin B (CB) or cytochalasin D (CD) under isosmotic condition the disruption of the F-actin integrity was observed, and I (Cl,swell) was not elicited. With combination treatment of CB with PMA, hyposmotic solution could not elicited I (Cl,swell) . The results suggested that the role of PTK, probably receptor tyrosine kinase, for regulation of I (Cl,swell) appeared to be at upstream site related to the role of F-actin. Then PKC signal pathway was activated somehow and finally change in the polymerization state of cytoskeleton led to activate the swelling-activated Cl − channels. These results demonstrate clearly that PTK, PKC and F-actin are important factors for regulation of I (Cl, swell) , in embryonic chick heart cells as compared with often controversial results reported in different cell types.

ClC-3-independent, PKC-dependent Activity of Volume-sensitive Cl^- Channel in Mouse Ventricular Cardiomyocytes

“…Similar downregulating effects of PKC activators have been observed for native VSOR Cl -currents recorded not only from rabbit and guinea pig cardiomyocytes [39,46] but also from other cell types [29,[47][48][49][50][51][52][53][54]. In contrast, the activity of VSOR Cl -channels in canine and chick cardiomyocytes [55,56], and many epithelial cells [57][58][59][60], has been reported to be enhanced by PKC activation. It is noteworthy that such opposite PKC dependency of native VSOR Cl -currents has been observed even in cells where ClC-3 is expressed [39,46,48,50,51,53,55,57].…”

Noninvasive assessment of cystic fibrosis–associated liver disease with acoustic radiation force impulse imaging

“…What is the mechanism by which tamoxifen inhibits I Cl,vol ? It has been revealed that protein kinase C (PKC) was involved in the activation of I Cl,vol (Shuba et al, 1996; Wei et al, 2003) and tamoxifen showed an inhibitory effects of on PKC (Horgan et al, 1986; Kuo et al, 2011). Would tamoxifen suppress I Cl,vol by inhibiting PKC?…”

“…Tamoxifen has been found to inhibit PKC activity for long time (O'Brian et al, 1985; Ramachandran et al, 2004). Down regulation of PKC activity could downregulate (Chou et al, 1998; Wei et al, 2003), upregulate (Shi et al, 2002; Xiong et al, 2009), or not affect I Cl,vol (Szucs et al, 1996; Leaney et al, 1997) in different cell lines. Is PKC involved in the inhibitory effect of tamoxifen on I Cl,vol in MHCC97H cells?…”

Antagonistic regulation of swelling-activated Cl−current in rabbit ventricle by Src and EGFR protein tyrosine kinases

“…I Cl,swell activated by mechanical stretch of rabbit ventricular myocytes is suppressed by acute application of either genistein or PP2 (7). On the other hand, genistein and PP2 stimulate swelling-induced I Cl,swell in human atrial myocytes (15), but genistein inhibits I Cl,swell in cultured embryonic chick heart (56). Thus the regulation of I Cl,swell is likely to depend on the method of stimulation (e.g., swelling vs. stretch) and the particular tissue studied.…”