Transcriptional regulation of sodium transport by vasopressin in renal cells

We base examined whether arginine vasopressin (AVP) can induce a long-term modulation of transepithelial ion transport in addition to its well known shortterm effect, In the RCCD1 rat cortical collecting duct cell line, an increase in both short-circuit current and Na-22 transport was observed after several hours of 10(-8) M AVP treatment (a concentration above the in vivo physiological range), This delayed effect was partially prevented by apical addition of 10(-5) M amiloride and was blocked by 10(-6) M actinomycin D and 2 x 10(-6) hr cycloheximide. The amounts of mRNA encoding the alpha(1) (not beta(1)) subunit of Na+/K+-ATPase and the beta and gamma (not alpha) subunits of the amiloride-sensitive epithelial Na+ channel were significantly increased by AVP treatment, The increase in mRNA was blocked by actinomycin D, not by amiloride, suggesting a Na+-independent increase in the rate of transcription of these subunits, The translation rates of the alpha(1) subunit of Na+/K+-ATPase and the beta and gamma subunits of the rat epithelial sodium channel increased significantly, whereas the translation rates of the other subunits remained unchanged, Finally, the number of Na+ channels present in the apical membrane of the cells increased, as demonstrated by enhanced specific [H-3]phenamil binding.