Superoxide increases surface nkcc2 in the rat thick ascending limbs via pkc.

SUPEROXIDE INCREASES SURFACE NKCC2 IN THE RAT THICK ASCENDING LIMBS VIA PKC. Am J Physiol Renal Physiol. 2019 May 15;: Authors: Haque MZ, Oritz P Abstract The apical Na/K/2Cl cotransporter NKCC2 mediates NaCl reabsorption by the thick ascending limbs (TAL). The free radical superoxide (O2-) stimulates TAL NaCl absorption by enhancing NKCC2 activity. In contrast, NO scavenges O2- and inhibits NKCC2. NKCC2 activity depends on the number of NKCC2 transporters in the TAL apical membrane and its phosphorylation. We hypothesized that O2- stimulates NKCC2 activity by enhancing apical surface NKCC2 expression. We measured surface NKCC2 expression in rat TALs by surface biotinylation and Western blot. Treatment of TALs with O2- produced by exogenous xanthine oxidase (1 mU/mL) and hypoxanthine (500 µM) stimulated surface NKCC2 expression by ~18±5% (p<0.05). O2- stimulated surface NKCC2 expression was blocked by the O2- scavenger tempol (50 µM). Scavenging H2O2 with 100 U/mL catalase did not block the stimulatory effect of xanthine oxidase/hypoxanthine (22±8% increase from control, p<0.05). Inhibition of endogenous NO production with L-nitro-methyl arginine (LNAME) enhanced surface NKCC2 expression by 21±6 and when added together with xanthine oxidase/hypoxanthine increased surface NKCC2 by 41±10% (p<0.05). Scavenging O2-, with superoxide dismutase (300 U/mL) decreased this stimulatory effect by 60% (39±4 to 15±10%, p<0.05)....
Source: Am J Physiol Renal P... - Category: Urology & Nephrology Authors: Tags: Am J Physiol Renal Physiol Source Type: research