SYNTHESIS AND LOCALIZATION OF C-TYPE NATRIURETIC PEPTIDE IN MAMMALIANKIDNEY

We have previously demonstrated the synthesis of atrial natriuretic fa ctor (ANF) in the distal cortical nephron of the rat kidney. We now re port the synthesis of C-type natriuretic peptide (CNP) in the rat, mou se, and human nephron. CNP mRNA was initially detected in the rat and mouse kidney, as well as in three transformed cell lines isolated from the proximal and distal nephron, using reverse transcription-polymera se chain reaction (RT-PCR). Confirmation of the kidney PCR product was performed by nucleotide sequence analysis and Southern hybridization. Northern hybridization of rat brain CNP cDNA to human kidney polyaden ylated RNA detected a 1.4-kb gene transcript. Rat nephron segments wer e microdissected and subjected to RT-PCR to localize CNP mRNA. CNP mRN A was detected in the proximal convoluted tubule, cortical collecting duct, medullary thick limbs, and inner medullary collecting ducts. CNP , as detected by immunohistochemistry, was found to colocalize with CN P mRNA.