Interrelation between membrane transport and the contents of alkali metal cations in HeLa cells.

Abstract

The relation of membrane

Rb+ influx in response to changes in energy generation: Effect of the regulation of the ATP content of HELa cells

“…As ouabain-sensitive Rb+ influx was 13.28 nmol/mg proteidmin, the ratio of the two values is 2.14, which is close to the value of 1.95 reported for Ehrlich ascites tumor cells in the presence of 2,4-dinitrophenol and quercetin (Suolinna et al, 1975). These values are consistent with reports that 2 mol of K + are moved per mol of ATP hydrolyzed in red cells (Sen and Post, 1964;Whittam and Ager, 1965) and 2 Rb+ ions are concomitantly transported by the Na,K-pump in HeLa cells (Ikehara et al, 1982). Furthermore, the value of about 2 suggests that active Rb+ influx is mainly supported by glycolysis in HeLa cells in the absence of glutamine.…”

“…As the K + content of HeLa cells decreases significantly with drop in the pump activity by only 20% (Ikehara et al, 1982), ATP must be strictly regulated to maintain unchanged pump activity. However, ATP is no longer rate-limiting when its content becomes supranormal on addition of adenosine, consistent with results reported for rabbit intestinal epithelium (Grasl et al, 1982).…”

“…On incubation for 2 h with the inhibitors, the cells gain Na' to different extents depending on the ATP contents below the normal level, as shown in Figure 7. As intracellular Naf is a potent activator of ouabain-sensitive Rb + uptake in HeLa cells (Ikehara et al, 1982), the slopes of the lines in Figure 4 could be those modified by the cation. The same argument is also valid for the results shown in Figure 6.…”

“…We investigated the effect of change in the ATP content on the intracellular Naf content, which was reported to stimulate the Na,K-pump activity in HeLa cells (Ikehara et al, 1982). Since the Na+ content was found in a previous experiment to reach a steady state in 2 h on treatment with CCCP, the cells were incubated for 2 h under the same conditions as for Table 3 and Figure 5 to alter the ATP and Na+ contents concomitantly.…”