Effects of hyposmotic shock on ion fluxes in isolated trout hepatocytes.
Isolated trout hepatocytes exposed to hypotonic Hank's medium (isotonicity x 0.70) swelled to 1.17 times the control volume after 3 min; by 15 min the cell volume had returned to normal. The ouabain-insensitive K+ uptake increased, indicating an immediate rise in K+ membrane permeability. As indicated by analysis of cellular contents, the regulatory volume decrease (RVD) was ensured by a release of intracellular K+. Na+ was not implicated in this mechanism. This potassium permeability induced by hypotonic shock was transient (maximum at 6 min), insensitive to blocking agents of voltage- and Ca2+-dependent K+ channels, and chloride-dependent. This result, together with a time-course of Cl- uptake similar to that of K+, suggests a K+/Cl- cotransport mechanism. This cotransport is inhibited by high furosemide concentrations (10(-3) mol l-1) but not by bumetanide (10(-4) mol l-1) or piretanide (10(-4) mol l-1).
Bianchini
L
L
Laboratoire de Physiologie Cellulaire et Comparée et UA CNRS 651, Faculté des Sciences, Nice, France.
Fossat
B
B
Porthé-Nibelle
J
J
Ellory
J C
JC
Lahlou
B
B
D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D007038:Hypotonic Solutions; D007424:Intracellular Fluid / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D014337:Trout
D002712:Chlorides; D007038:Hypotonic Solutions; D012964:Sodium; D012413:Rubidium; D011188:Potassium