Effects of protein kinase and phosphatase inhibitors and anti-L antisera on K+ transport in LK sheep red cells

We investigated the role of protein phosphorylation in the action of anti-L on low potassium (LK) sheep red cells. Anti-L stimulated the Na/K pump by four- to fivefold, but Na/K pump activity in anti-L-stimulated or in contro l cells was unaffected by protein kinase/protein phosphatase (PK/PP) inhibi tors. KCI co-transport activity was inhibited by anti-L (about 50%). Go-tra nsport was stimulated by staurosporine; and inhibited by calyculin A, okada ic acid, tyrphostin B46 and genistein; with a similar pattern in both contr ol and anti-L-treated cells. O-2 sensitivity of KCl co-transport was simila r in control and anti-L-treated cells. Neither control nor anti-L-stimulate d Na/K pump activities were O-2 sensitive. Incubation with urea stimulated KCI co-transport in both control and anti-L-treated cells. Inhibition of co -transport by anti-L was unaffected by low concentrations of urea but was r educed at higher urea concentrations. Na/K pump activity of control cells w as unaffected by incubation with urea, but that in cells stimulated by anti -L was reduced, though not significantly. Under high hydrostatic pressure, KCI co-transport was stimulated, and the inhibitory effects of PP inhibitio n (okadaic acid), anti-L or combinations of the two were reduced. Results s uggest that anti-L does not affect K+ transport in LK sheep red cells via p rotein phosphorylation. (C) 2000 Elsevier Science S.A. All rights reserved.