Renal nitric oxide production in rat pregnancy: role of constitutive nitric oxide synthases.
Smith-CA; Santymire-B; Erdely-A; Venkat-V; Losonczy-G; Baylis-C
Am J Physiol Renal Physiol 2010 Oct; 299(4):F830-F836
Functional studies show that increased renal nitric oxide (NO) mediates the renal vasodilation and increased glomerular filtration rate that occur during normal pregnancy. We investigated whether changes in the constitutive NO synthases (NOS), endothelial (eNOS) and neuronal (nNOS), were associated with the increased renal NO production in normal midterm pregnancy in the rat. In kidneys from midterm pregnant (MP: 11-13 days gestation), late-term pregnant (LP: 18-20 days gestation), and similarly aged virgin (V) rats, transcript and protein abundance for eNOS and the nNOSa and nNOS▀ splice variants, as well as the rate of L-arginine-to-L-citrulline conversion, were determined as a measure of NOS activity. At MP, renal cortical abundance of the total eNOS protein and phosphorylated (Ser(1177)) eNOS was reduced, and L-arginine-to-L-citrulline conversion in the cortical membrane fraction was decreased; these declines were also seen in LP. There were no changes in the eNOS transcript. In contrast, L-arginine-to-L-citrulline conversion in the soluble fraction of renal cortex increased at MP and then declined at LP. This MP increase was ablated by S-methylthiocitrulline, a nNOS inhibitor. Using Western blotting, we did not detect a change in the protein abundance or transcript of the 160-kDa nNOSa, but protein abundance and transcript of the nNOS▀ were increased at MP in cortex. Collectively, these studies suggest that the soluble nNOS▀ is responsible for the increased renal cortical NO production during pregnancy.
Reproductive-system; Animals; Animal-studies; Kidney-function; Kidneys; Laboratory-animals;
Author Keywords: Endothelial nitric oxide synthase; Neuronal nitric oxide synthase; L-arginine-to-L-citrulline conversion; S-methylthiocitrulline; Splice variants
C. Baylis, 1600 SW Archer Rd., Univ. of Florida, POB 100274, Gainesville, FL 32667
American Journal of Physiology: Renal Physiology