Nitric oxide reduces renal pendrin abundance

Abstract

Pendrin is an angiotensin II-sensitive intercalated cell Cl− transporter that modulates blood pressure. We showed that angiotensin type 1 receptor inhibitors reduce renal pendrin total protein abundance in mice in vivo through a nitric oxide (NO)-dependent mechanism. We used western blots and immunohistochemistry to determine if NO modulates renal pendrin expression in vivo. Nitric oxide synthase inhibitor (L-NAME, 0.4 mg/d) administration for 7 d increased pendrin total protein abundance ~25%, without changing its subcellular distribution. To study pendrin's regulation in vitro, we dissected and cultured mouse cortical collecting ducts (CCDs) and connecting tubules (CNTs) up to 18 hrs. After 18 hrs of culture, CCDs maintain a tubule structure and a steep solute gradient when perfused in vitro. Thus, we quantified pendrin protein abundance by confocal fluorescent microscopy in tubules from furosemide-treated mice after 0–18 hrs of culture. Pendrin protein abundance is relatively stable in untreated CCDs and CNTs during 18 hrs of culture but increases 67% in CNT and 53% in CCD with 18 hrs of L-NAME administration (100 μM). Conversely, NO donor (DETA NONOate, 200 μM) application (18 hrs) reduces pendrin protein in CCD 36%. Thus, NO reduces pendrin protein abundance in CNT and CCD in vivo and in vitro. The signaling mechanism by which this occurs remains to be determined.