Cultured cells from renal cortex of hibernators and nonhibernators. Regulation of cell K+ at low temperature.
Cells were grown as primary monolayer cultures from kidney cortex of guinea pigs (nonhibernators), hamsters and ground squirrels (both hibernating species). When plates of cells were placed at 5 degrees C, cells of guinea pigs lost 37% of their K+ in 2 h and those of the hibernator lost about 10%. Uptake of 42K into the cells exhibited a simple, single exponential time course at both temperatures. Unidirectional efflux of K+ was equal to K+ influx in all cultures at 37 degrees C and, within limits of error, in hibernator cells at 5 degrees C. Efflux was 3-to 5-fold greater than influx in guinea pig cells at 5 degrees C. After 2 h in the cold the ouabain sensitive K+ influx remaining (7-15% of that at 37 degrees C) was about the same in the cells of the 3 species. Cells from active hamsters and from hibernating ground squirrels, however, exhibited significantly greater pump activity after 45 min in the cold (19 and 14%, respectively). The stimulation of K+ influx by increasing [K+] did not show an increase in Km+ at 5 degrees C in cells of guinea pigs and ground squirrels. Lowering [K+]c and/or raising [Na+]c by treatment in low- and high-K+ media caused only slight stimulation of K+ influx, except in cells of ground squirrels at 5 degrees C in which the stimulation was at least 11-times greater than at 37 degrees C or in cells of guinea pigs at either temperature. This altered kinetic response of K+ transport to cytoplasmic ion stimulation with cooling accounted for about one-third of the improved regulation of K+ at 5 degrees C in ground squirrel cells; the other two-thirds was attributable to a greater decrease in K+ leak with cooling. The inhibition of active transport by cold in all 3 species was much less severe than that previously seen in any (Na++K+)-ATPase of mammalian cells.
D000818:Animals; D001693:Biological Transport, Active; D002478:Cells, Cultured; D006224:Cricetinae; D006168:Guinea Pigs; D006605:Hibernation; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D008433:Mathematics; D008647:Mesocricetus; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012589:Sciuridae; D012964:Sodium / Q000378:metabolism; D013045:Species Specificity; D013696:Temperature
D010042:Ouabain; D012964:Sodium; D011188:Potassium