AJP - Heart and Circulatory Physiology, Vol 268, Issue 2 628-H632, Copyright © 1995 by American Physiological Society

ARTICLES

Increased thromboxane-mediated contractions of retinal vessels of newborn pigs to peroxides

D. Abran, D. R. Varma and S. Chemtob
Centre de Recherche, Hopital Sainte-Justine, Montreal, Quebec, Canada.

The vasomotor effects of three peroxides (H2O2, cumene hydroperoxide, and t-butyl hydroperoxide) on the retinal vasculature, as well as the role of thromboxane in these effects, were studied using time-frame photography of isolated eyecup preparations from newborn and adult pigs. All three peroxides caused constriction of retinal arteries and veins, and these effects were greater in the newborn than in the adult. The cyclooxygenase inhibitor indomethacin, the thromboxane synthase blocker CGS-13080, and the thromboxane receptor blockers GR-32191B and L-670,596 inhibited the peroxide-induced vasoconstriction. The peroxides also increased thromboxane levels in the retina, and this increase was greater in newborn than in adult tissues. Both indomethacin and CGS-13080 prevented the peroxide-induced increase in retinal thromboxane. The thromboxane analogue U-46619 also produced constriction of newborn and adult retinal vessels, but its effects on the retinal veins of newborn pigs were less than those on adult veins. Data indicate an important role for increased production of thromboxane in the relative increase in the vasoconstrictor effects of peroxides on the newborn retinal vasculature. These findings suggest that the vasoconstriction and occlusion after oxidative stresses, which precede retinal neovascularization, are mediated by thromboxane.

This article has been cited by other articles:

				X. Hou, F. Gobeil Jr., A. M. Marrache, C. Quiniou, S. Brault, D. Checchin, S. G. Bernier, F. Sennlaub, J.-S. Joyal, D. Abran, et al. Increased platelet-activating factor-induced periventricular brain microvascular constriction associated with immaturity Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2003; 284(4): R928 - R935. [Abstract] [Full Text] [PDF]

				D. H. Wright, D. Abran, M. Bhattacharya, X. Hou, S. G. Bernier, A. Bouayad, J.-C. Fouron, A. Vazquez-Tello, M. H. Beauchamp, R. I. Clyman, et al. Prostanoid receptors: ontogeny and implications in vascular physiology Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2001; 281(5): R1343 - R1360. [Abstract] [Full Text] [PDF]

				X. Hou, L. J. Roberts II, D. F. Taber, J. D. Morrow, K. Kanai, F. Gobeil Jr., M. H. Beauchamp, S. G. Bernier, G. Lepage, D. R. Varma, et al. 2,3-Dinor-5,6-dihydro-15-F2t-isoprostane: a bioactive prostanoid metabolite Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2001; 281(2): R391 - R400. [Abstract] [Full Text] [PDF]

				I. Lahaie, P. Hardy, X. Hou, H. Hassessian, P. Asselin, P. Lachapelle, G. Almazan, D. R. Varma, J. D. Morrow, L. J. Roberts II, et al. A novel mechanism for vasoconstrictor action of 8-isoprostaglandin F2alpha on retinal vessels Am J Physiol Regulatory Integrative Comp Physiol, May 1, 1998; 274(5): R1406 - R1416. [Abstract] [Full Text] [PDF]

				P. Hardy, K. G. Peri, I. Lahaie, D. R. Varma, and S. Chemtob Increased Nitric Oxide Synthesis and Action Preclude Choroidal Vasoconstriction to Hyperoxia in Newborn Pigs Circ. Res., September 1, 1996; 79(3): 504 - 511. [Abstract] [Full Text]