The purpose of this study was to test the hypothesis that increased flow through coronary arterioles increases endothelial cell nitric oxide synthase (ecNOS) and Cu/Zn superoxide dismutase (SOD) mRNA expression. Single porcine coronary arterioles (ID 100-160 µm; pressurized) were cannulated, perfused, and exposed to intraluminal flow sufficient to produce maximal flow-induced dilation of coronary arterioles (high flow; 7.52 ± 0.22 µl/min), low flow (0.84 ± 0.05 µl/min), or no flow for 2 or 4 h. Mean shear stress was calculated to be 5.7 ± 1.0 dyn/cm² for high-flow arterioles and 1.6 ± 1.0 dyn/cm² for low-flow arterioles. At the end of the treatment period, mRNA was isolated from each vessel, and ecNOS and SOD mRNA expression was assessed using a semiquantitative RT-PCR. All data were standardized by coamplifying ecNOS or SOD with glyceraldehyde-3-phosphate dehydrogenase. The results indicate that ecNOS mRNA expression is increased in arterioles exposed to 2 or 4 h of high flow. In contrast, SOD mRNA expression was increased only after 4 h of high flow. Neither gene is induced by exposure to low flow. On the basis of these data, we concluded that ecNOS and SOD mRNA expression is regulated by flow in porcine coronary arterioles. In addition, we concluded that a threshold level of flow and shear stress must be sustained to elicit the upregulation of ecNOS and SOD mRNA expression.

gene expression; reverse transcription polymerase chain reaction; complementary deoxyribonucleic acid synthesis; endothelium-derived relaxing factor; superoxide dismutase

This article has been cited by other articles:

				J.-L. Balligand, O. Feron, and C. Dessy eNOS Activation by Physical Forces: From Short-Term Regulation of Contraction to Chronic Remodeling of Cardiovascular Tissues Physiol Rev, April 1, 2009; 89(2): 481 - 534. [Abstract] [Full Text] [PDF]

				L. Ai, M. Rouhanizadeh, J. C. Wu, W. Takabe, H. Yu, M. Alavi, R. Li, Y. Chu, J. Miller, D. D. Heistad, et al. Shear stress influences spatial variations in vascular Mn-SOD expression: implication for LDL nitration Am J Physiol Cell Physiol, June 1, 2008; 294(6): C1576 - C1585. [Abstract] [Full Text] [PDF]

				M. H. Laughlin, S. C. Newcomer, and S. B. Bender Importance of hemodynamic forces as signals for exercise-induced changes in endothelial cell phenotype J Appl Physiol, March 1, 2008; 104(3): 588 - 600. [Abstract] [Full Text] [PDF]

				C. Yan, A. Huang, G. Kaley, and D. Sun Chronic high blood flow potentiates shear stress-induced release of NO in arteries of aged rats Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H3105 - H3110. [Abstract] [Full Text] [PDF]

				S. C. Newcomer, U. A. Leuenberger, C. S. Hogeman, and D. N. Proctor Heterogeneous vasodilator responses of human limbs: influence of age and habitual endurance training Am J Physiol Heart Circ Physiol, July 1, 2005; 289(1): H308 - H315. [Abstract] [Full Text] [PDF]

				C. R. Woodman, E. M. Price, and M. H. Laughlin Shear stress induces eNOS mRNA expression and improves endothelium-dependent dilation in senescent soleus muscle feed arteries J Appl Physiol, March 1, 2005; 98(3): 940 - 946. [Abstract] [Full Text] [PDF]

				P. G. Lloyd, B. M. Prior, H. Li, H. T. Yang, and R. L. Terjung VEGF receptor antagonism blocks arteriogenesis, but only partially inhibits angiogenesis, in skeletal muscle of exercise-trained rats Am J Physiol Heart Circ Physiol, February 1, 2005; 288(2): H759 - H768. [Abstract] [Full Text] [PDF]

				J. D. Symons, Y. Hayashi, and J. L. Ensunsa Improved coronary vascular function evoked by high-intensity treadmill training is maintained in arteries exposed to ischemia and reperfusion J Appl Physiol, October 1, 2003; 95(4): 1638 - 1647. [Abstract] [Full Text] [PDF]

				J. Ma, C. I. Kahwaji, Z. Ni, N. D. Vaziri, and R. E. Purdy Effects of simulated microgravity on arterial nitric oxide synthase and nitrate and nitrite content J Appl Physiol, January 1, 2003; 94(1): 83 - 92. [Abstract] [Full Text] [PDF]

				M. H. Laughlin, L. J. Rubin, J. W. E. Rush, E. M. Price, W. G. Schrage, and C. R. Woodman Short-term training enhances endothelium-dependent dilation of coronary arteries, not arterioles J Appl Physiol, January 1, 2003; 94(1): 234 - 244. [Abstract] [Full Text] [PDF]

				C. R. Woodman, E. M. Price, and M. H. Laughlin Aging induces muscle-specific impairment of endothelium-dependent dilation in skeletal muscle feed arteries J Appl Physiol, November 1, 2002; 93(5): 1685 - 1690. [Abstract] [Full Text] [PDF]

				H. T. Yang, J. Ren, M. H. Laughlin, and R. L. Terjung Prior exercise training produces NO-dependent increases in collateral blood flow after acute arterial occlusion Am J Physiol Heart Circ Physiol, January 1, 2002; 282(1): H301 - H310. [Abstract] [Full Text] [PDF]

				C. R. Woodman, W. G. Schrage, J. W. E. Rush, C. A. Ray, E. M. Price, E. M. Hasser, and M. H. Laughlin Hindlimb unweighting decreases endothelium-dependent dilation and eNOS expression in soleus not gastrocnemius J Appl Physiol, September 1, 2001; 91(3): 1091 - 1098. [Abstract] [Full Text] [PDF]

				J. L. Tuttle, R. D. Nachreiner, A. S. Bhuller, K. W. Condict, B. A. Connors, B. P. Herring, M. C. Dalsing, and J. L. Unthank Shear level influences resistance artery remodeling: wall dimensions, cell density, and eNOS expression Am J Physiol Heart Circ Physiol, September 1, 2001; 281(3): H1380 - H1389. [Abstract] [Full Text] [PDF]

				L. R. Johnson, J. W. E. Rush, J. R. Turk, E. M. Price, and M. H. Laughlin Short-term exercise training increases ACh-induced relaxation and eNOS protein in porcine pulmonary arteries J Appl Physiol, March 1, 2001; 90(3): 1102 - 1110. [Abstract] [Full Text] [PDF]

				M. H. Laughlin, J. S. Pollock, J. F. Amann, M. L. Hollis, C. R. Woodman, and E. M. Price Training induces nonuniform increases in eNOS content along the coronary arterial tree J Appl Physiol, February 1, 2001; 90(2): 501 - 510. [Abstract] [Full Text] [PDF]

				J. W. E. Rush, M. H. Laughlin, C. R. Woodman, and E. M. Price SOD-1 expression in pig coronary arterioles is increased by exercise training Am J Physiol Heart Circ Physiol, November 1, 2000; 279(5): H2068 - H2076. [Abstract] [Full Text] [PDF]

				W. G. Schrage, C. R. Woodman, and M. H. Laughlin Hindlimb unweighting alters endothelium-dependent vasodilation and ecNOS expression in soleus arterioles J Appl Physiol, October 1, 2000; 89(4): 1483 - 1490. [Abstract] [Full Text] [PDF]

				V. Hampl and J. Herget Role of Nitric Oxide in the Pathogenesis of Chronic Pulmonary Hypertension Physiol Rev, October 1, 2000; 80(4): 1337 - 1372. [Abstract] [Full Text] [PDF]

				Z. Cai, J. Xin, D. M. Pollock, and J. S. Pollock Shear stress-mediated NO production in inner medullary collecting duct cells Am J Physiol Renal Physiol, August 1, 2000; 279(2): F270 - F274. [Abstract] [Full Text] [PDF]

				M. R. McCurdy, P. N. Colleran, J. Muller-Delp, and M. D. Delp Physiology of a Microgravity Environment: Selected Contribution: Effects of fiber composition and hindlimb unloading on the vasodilator properties of skeletal muscle arterioles J Appl Physiol, July 1, 2000; 89(1): 398 - 405. [Abstract] [Full Text] [PDF]

				L. R. Johnson, J. L. Parker, and M. H. Laughlin Chronic exercise training improves ACh-induced vasorelaxation in pulmonary arteries of pigs J Appl Physiol, February 1, 2000; 88(2): 443 - 451. [Abstract] [Full Text] [PDF]

				J. L. Jasperse, C. R. Woodman, E. M. Price, E. M. Hasser, and M. H. Laughlin Hindlimb unweighting decreases ecNOS gene expression and endothelium-dependent dilation in rat soleus feed arteries J Appl Physiol, October 1, 1999; 87(4): 1476 - 1482. [Abstract] [Full Text] [PDF]