A novel role for protein phosphatase 2A in the dopaminergic regulation of Na,K-ATPase

Stimulation of dopaminergic type 1 (D-1) receptors increases lung edema cle arance by regulating Na,K-ATPase function in the alveolar epithelium. We st udied the role of serine/threonine protein phosphatases in the Na,K-ATPase regulation by D-1 agonists in A549 cells. We found that low doses of the ty pe 1/2A protein phosphatase inhibitor okadaic acid as well as SV40 small t antigen transiently transfected into A549 cells prevented the D-1 agonist-i nduced increase in Na,K-ATPase activity and translocation from intracellula r pools to the plasma membrane. This was associated with a rapid and transi ent increase in protein phosphatase 2A activity. We conclude that D-1 stimu lation regulates Na,K-ATPase activity by promoting recruitment of Na,K-ATPa ses from intracellular pools into the basolateral membranes of A549 tells v ia a type 2A protein phosphatase, (C) 2000 Federation of European Biochemic al Societies, Published by Elsevier Science B.V. All rights reserved.