Alterations in monovalent cation transport in Sindbis virus-infected chick cells.
Influx experiments using the potassium tracer 86Rb+ indicated that the activity of the Na+K+ ATPase, or sodium pump, was reduced 40-50% as a consequence of Sindbis virus infection of avian fibroblasts. The inhibition of this ouabain-sensitive, active transport system temporally correlated with a decrease in the intracellular K+ concentration and the termination of cellular protein synthesis. By contrast, the rate of influx facilitated by the furosemide-sensitive (Na+K+Cl-) cotransport system was only slightly depressed. Efflux experiments indicated that no alterations in the relative rate of nonspecific permeability or "leakage" of K+ could be detected in chick cells infected by Sindbis virus. The amount of [3H]ouabain bound to Sindbis virus-infected cells paralleled the reduction in Na+K+ ATPase activity. These binding studies revealed no difference in the number of Na+ pump sites. The Km of ouabain binding, however, increased approximately 3.5-fold in the virus-infected cells. No change in the apparent affinity of the Na+ pump for K+ could be detected, yet the Vmax for ouabain-sensitive K+ transport was decreased. These experiments suggest that a reduction in Na+K+ ATPase turnover results in the altered intracellular monovalent cation levels found in Sindbis virus-infected chick cells.
D000818:Animals; D001693:Biological Transport, Active; D002414:Cations, Monovalent / Q000378:metabolism*; D002642:Chick Embryo; D002712:Chlorides / Q000378:metabolism; D005665:Furosemide / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012845:Sindbis Virus; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D014036:Togaviridae Infections / Q000378:metabolism*
D002414:Cations, Monovalent; D002712:Chlorides; D010042:Ouabain; D005665:Furosemide; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium