NEURONAL NITRIC-OXIDE SYNTHASE IS EXPRESSED IN PRINCIPAL CELL OF COLLECTING DUCT

We used the RT-PCR technique and immunocytochemical methods to determi ne the expression of endothelial nitric oxide synthase (eNOS) or neuro nal nitric oxide synthase (nNOS) in the cortical collecting duct (CCD) in rats on high-K+ diet. The microdissected CCDs of the rat kidney we re lysed, and RT-PCR was carried out using rat nNOS and eNOS gene-spec ific primers. Southern analysis showed the presence of mRNA of nNOS bu t not eNOS in the CCD. The presence of nNOS in the CCD was further con firmed by light microscopy. We used the polyclonal nNOS antibody in im munocytochemical studies of the isolated CCD. We found that immunoreac tivity to nNOS was present in the CCD and heterogeneous with positive and negative immunostaining. We performed the immunocytochemical studi es in the split-open CCD and found that the immunoreactivity to nNOS w as detected only in principal cells but not in intercalated cells. We conclude that nNOS is expressed in the rat CCD in rats on high-K+ diet . The presence of nNOS in the CCD is heterogeneous and mainly located in principal cells.