Biphasic effect of PGF2a on the basolateral 40 pS K channel (a heterotetramer of Kir4.1 and Kir5.1) in the early distal convoluted tubule (DCT1) (1109.9)

We used the patch‐clamp technique to examine the effect of PGF2α on the basolateral 40 pS K channel in the DCT1. Application of PGF2α at concentrations lower than 500 nM stimulated the 40 pS K channel. The stimulatory effect of PGF2α was abolished by inhibiting src‐family protein kinase (SFK) and NADPH oxidase. Moreover, adding 100 μM H 2 O 2 mimicked the effect of PGF2α and increased the 40 pS K channel activity in DCT1 and augmented whole cell K currents in HEK293 cells transfected with KCNJ10/16 which are known to form the heterotetramer in the basolateral membrane of DCT1. The inhibition of SFK also blocked the stimulatory effect of H 2 O 2 on the basolateral 40 pS K channel in DCT1. The role of SFK in mediating the effect of H 2 O 2 on the 40 pS K channel was further indicated by the observation that H 2 O 2 failed to stimulate the K channels in cells transfected with KCNJ16+KCNJ10Y9F in which tyrosine phosphorylation site was mutated. This suggests that PGF2α and H 2 O 2 stimulate the basolateral 40 pS K channel in DCT1 by SFK‐induced phosphorylation of KCNJ10. While PGF2α stimulates the K channels at low dose, PGF2α at high dose (>1 uM) inhibited the basolateral K channels. The inhibitory effect of PGF2α was abolished by inhibiting PKC. We conclude that PGF2α at low doses stimulates the basolateral 40 pS K channel by a SFK‐dependent pathway, while at high concentrations it inhibited the K channel in the DCT1 by a PKC‐dependent pathway. Grant Funding Source : NIH