Abstract
Dogfish shark (Squalus acanthias) rectal gland cells swell massively when incubated in elasmobranch media in which Na+ was equivalently replaced by K+; this swelling was abolished when the impermeant gluconate replaced Cl-, while the cell depolarization was comparable in both media. The K+-effect was associated with (a) an increase of the steady-state 42K (and 86Rb) efflux (particularly of the rate constant of the fast cellular efflux component) and a rearrangement of the respective cellular pools of K+; (b) an alteration of cell morphology and the pattern of the F-actin staining along the basolateral cell membrane as revealed with fluorescent analogs of phallacidin. These changes were independent of cell volume, being identical in KCl and K-gluconate media. The observations were specific for K+ (and Rb+): replacement of media Na+ by Li+ (which is not actively extruded by the cells), or the presence of ouabain, produced only minor swelling without affecting cell morphology and F-acting distribution. The results are consistent with the following view: as opposed to Na+ or Li+ media, the K+-induced changes of the cortical F-actin component of the cytoskeleton permit the observed massive cell swelling due to the osmotic contribution of intracellular impermeant anion(s).
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More From: Biochimica et Biophysica Acta (BBA) - Molecular Cell Research
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