Expression of endothelial nitric oxide synthase in the postnatal developing porcine kidney

The postnatal pattern of renal endothelial nitric oxide synthase (eNOS) is unknown. The purpose of this study was to characterize eNOS expression duri ng maturation and compare this to neuronal NOS (nNOS). The experiments meas ured whole kidney eNOS mRNA expression by RT-PCR and protein content by Wes tern blot, as well as cortical and medullary protein content in piglets at selected postnatal ages and in adult pigs. Whole kidney eNOS mRNA was compa red with nNOS. Whole kidney eNOS expression decreased from the newborn to i ts lowest at 7 days, returning by 14 days to adult levels. This eNOS mRNA p attern contrasted with nNOS, which was highest at birth, and progressively decreased to its lowest level in the adult. At birth, cortical eNOS protein was greater than medullary, contrasting with the adult pattern of equivale nt levels. In conclusion eNOS is developmentally regulated during early ren al maturation and may critically participate in renal function during this period. The eNOS developmental pattern differs from nNOS, suggesting that t hese isoforms may have different regulatory factors and functional contribu tions in the postnatal kidney.