Immunostimulants trigger vascular smooth muscle cells (VSMC) to express the inducible isoform of NO synthase (iNOS) and increased arginine transport activity. Although arginine transport in VSMC is considered to be mediated via the y⁺ system, we show here that rat VSMC in culture express the cat-1 gene transcript as well as an alternatively spliced transcript of the cat-2 gene. An RT-PCR cloning sequence strategy was used to identify a 141-base nucleotide sequence encoding the low-affinity domain of alternatively spliced CAT-2A and a 138-base nucleotide sequence encoding the high-affinity domain of CAT-2B in VSMC activated with lipopolysaccharide (LPS) in combination with interferon- (IFN). With this sequence as a probe, Northern analyses showed that CAT-1 mRNA and CAT-2B mRNA are constitutively present in VSMC, and the expression of both mRNAs was rapidly stimulated by treatment with LPS-IFN, peaked within 4 h, and decayed to basal levels within 6 h after LPS-IFN. CAT-2A mRNA was not detectable in unstimulated or stimulated VSMC. Arginine transporter activity significantly increased 4-10 h after LPS-IFN. iNOS activity was reduced to almost zero in the absence of extracellular arginine uptake via system y⁺. Induction of arginine transport seems to be a prerequisite to the enhanced synthesis of NO in VSMC. Moreover, this work demonstrates tissue expression of CAT mRNAs with use of a model of LPS injection in rats. RT-PCR shows that the expression of CAT-1 and CAT-2B mRNA in the lung, heart, and kidney is increased by LPS administration to rats, whereas CAT-2A mRNA is abundantly expressed in the liver independent of LPS treatment. These findings suggest that together CAT-1 and CAT-2B play an important role in providing substrate for high-output NO synthesis in vitro as well as in vivo and implicate a coordinated regulation of intracellular iNOS enzyme activity with membrane arginine transport.

nitric oxide synthase; arginine; inducible isoform of nitric oxide synthase

This article has been cited by other articles:

				K. A. Munger, R. C. Blantz, and M. J. Lortie Acute renal response to LPS: impaired arginine production and inducible nitric oxide synthase activity Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2006; 291(3): R684 - R691. [Abstract] [Full Text] [PDF]

				K. P. Stanley, L. G. Chicoine, T. L. Young, K. M. Reber, C. R. Lyons, Y. Liu, and L. D. Nelin Gene transfer with inducible nitric oxide synthase decreases production of urea by arginase in pulmonary arterial endothelial cells Am J Physiol Lung Cell Mol Physiol, February 1, 2006; 290(2): L298 - L306. [Abstract] [Full Text] [PDF]

				S. C. Schafer, T. Wallerath, E. I. Closs, C. Schmidt, P. M. Schwarz, U. Forstermann, and H.-A. Lehr Dexamethasone suppresses eNOS and CAT-1 and induces oxidative stress in mouse resistance arterioles Am J Physiol Heart Circ Physiol, January 1, 2005; 288(1): H436 - H444. [Abstract] [Full Text] [PDF]

				M. J. Lortie, J. Satriano, F. B. Gabbai, S. Thareau, S. Khang, A. Deng, D. P. Pizzo, S. C. Thomson, R. C. Blantz, and K. A. Munger Production of arginine by the kidney is impaired in a model of sepsis: early events following LPS Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2004; 287(6): R1434 - R1440. [Abstract] [Full Text] [PDF]

				D. Schwartz, I. F. Schwartz, E. Gnessin, Y. Wollman, T. Chernichovsky, M. Blum, and A. Iaina Differential regulation of glomerular arginine transporters (CAT-1 and CAT-2) in lipopolysaccharide-treated rats Am J Physiol Renal Physiol, April 1, 2003; 284(4): F788 - F795. [Abstract] [Full Text] [PDF]

				G. E. Mann, D. L. Yudilevich, and L. Sobrevia Regulation of Amino Acid and Glucose Transporters in Endothelial and Smooth Muscle Cells Physiol Rev, January 1, 2003; 83(1): 183 - 252. [Abstract] [Full Text] [PDF]

				S. Calatayud, E. Garcia-Zaragoza, C. Hernandez, E. Quintana, V. Felipo, J. V. Esplugues, and M. D. Barrachina Downregulation of nNOS and synthesis of PGs associated with endotoxin-induced delay in gastric emptying Am J Physiol Gastrointest Liver Physiol, December 1, 2002; 283(6): G1360 - G1367. [Abstract] [Full Text] [PDF]

				P. O. Scumpia, P. J. Sarcia, V. G. DeMarco, B. R. Stevens, and J. W. Skimming Hypothermia attenuates iNOS, CAT-1, CAT-2, and nitric oxide expression in lungs of endotoxemic rats Am J Physiol Lung Cell Mol Physiol, December 1, 2002; 283(6): L1231 - L1238. [Abstract] [Full Text] [PDF]

				L. D. Nelin, H. E. Nash, and L. G. Chicoine Cytokine treatment increases arginine metabolism and uptake in bovine pulmonary arterial endothelial cells Am J Physiol Lung Cell Mol Physiol, November 1, 2001; 281(5): L1232 - L1239. [Abstract] [Full Text] [PDF]

				J. Fernandez, I. Yaman, R. Mishra, W. C. Merrick, M. D. Snider, W. H. Lamers, and M. Hatzoglou Internal Ribosome Entry Site-mediated Translation of a Mammalian mRNA Is Regulated by Amino Acid Availability J. Biol. Chem., April 6, 2001; 276(15): 12285 - 12291. [Abstract] [Full Text] [PDF]

				J. Fernandez, I. Yaman, W. C. Merrick, A. Koromilas, R. C. Wek, R. Sood, J. Hensold, and M. Hatzoglou Regulation of Internal Ribosome Entry Site-mediated Translation by Eukaryotic Initiation Factor-2alpha Phosphorylation and Translation of a Small Upstream Open Reading Frame J. Biol. Chem., January 11, 2002; 277(3): 2050 - 2058. [Abstract] [Full Text] [PDF]