REDUCED SODIUM-PUMP ACTIVITY IN INOSITOL-DEFICIENT HL-60 CELLS - NO EVIDENCE OF CONTROL BY PROTEIN-KINASE-C

HL-60 cells were cultured in normal and inositol-deficient media. The inositol-deficient cells showed reduced sodium pump activity, as measu red by ouabain-sensitive Rb-86+ uptake. The protein kinase C inhibitor s staurosporine and H7 did not affect uptake in either normal or inosi tol-deficient cells. However, U73122, a steroidal inhibitor of phospho inositidase C, inhibited uptake in both types of cells. Activators of protein kinase C had no effect on Rb+ entry. The inositol deficiency i s not considered to affect the sodium pump by a mechanism involving di acylglycerol and protein kinase C.