Caveolin-1 modulated renal nitric oxide synthase during hemorrhagic shock with aging

NOELIA ARRECHE; A FELLET,; BALASZCZUK A,

Congreso; 24th European Meeting of Hypertension; 2014

Endothelial nitric oxide synthase (eNOS)-mediated NO production plays a critical role in the regulation of renal function and pathophysiology. Studies demonstrated direct interaction of eNOS with caveolin-1 and it functions as an endogenous negative regulator of eNOS activity. A decrease in or an absence of caveolin-1 was shown to potentiate basal and agonist-stimulated eNOS activity. Aside from absolute changes in caveolin abundance, it is also important to consider whether alteration in the tissular and subcellular distribution of caveolin-1 would influence NOS activity. NO system and caveolin-1 have been identified as modulators of the normal aging process. Objective: In the present study, we evaluated the effect of caveolin -1 on the activity of renal NO system following acute renal hemorrhage with aging. Methods: Groups of young and adult animals: Group C, controls rats anesthetized; Group H : anesthetized rats subjected to acute hemorrhage of 20% of blood volume . At 120 min proceeded to the slaughter of animals and the removal of the kidney. The potential ability to produce NO by the renal tissue was assessed by measuring NOS activity (in vitro method and NADPH-diaphorase assay). Protein levels of the isoforms of NOS and caveolin -1 was determined by Western blot. To assess the potential for the association of eNOS with the inhibitory protein caveolin-1 in rat ventricles in situ, eNOS was immunoprecipitated with anti-caveolin-1 antibodies from whole kidney extracts of young and aged rats. Results: Aging decreases renal NOS activity, while the hypovolemic state causes an increase in this parameter in both young and adult animals (Group C young : 309 ± 24 pmol.g tej -1.min -1 Group H young : 499 ± 20 * pmol.g tej -1.min- 1, Group C adult: 249 ± 17 ≠ pmol.g tej -1.min- 1, Group H adult: 449 ± 16 * pmol.g tej -1.min -1 , *p < 0.01 vs. group C of each age group ; ≠ p < 0.01 vs. young group C). The changes observed in NOS activity were at the expense of changes in NADPH diaphorase histochemical activity in the renal medulla. No changes were observed in the protein levels of the isoforms of NOS and caveolin-1 in any groups. The study immunocolocalization of eNOS and caveolin -1 showed that: a) there was an increased association of eNOS with caveolin-1 in the adult C Group about young , b) acute hemorrhage of 20% of blood volume caused a greater dissociation of the complex eNOS/caveolin-1 in both age groups. Conclusion: The present study demonstrated the involvement of allosteric modulator, caveolin-1, in the regulation of renal NOS activity in hypovolemic state and aging. The reduced NOS activity observed in aged rats could be due to increased association of eNOS with caveolin-1. The hypovolemic state constitutes a stimulus for the dissociation of complex eNOS/caveolina-1 adjusting NO production to the needs of renal tissue to acute hemorrhage. This response was independent of age.