El estado hipovolémico modula la actividad y la expresión de la óxido nítrico sintetasa en el sistema cardiovascular

background we have previously demonstrated that pre-treatment with the nitric oxide synthase (nos) inhibitor ng-nitro-l-arginine- methyl ester (l-name), reverted hypotension and minimized hemorrhage-induced heart rate changes. study aim to evaluate the histochemical activity (nadph-diaforase method) and expression (western blot) of nos in right atrium (a) and left ventricle (v) of animals subjected to a 20% loss of the total blood volume. methods we included four groups of animals (n = 14 per group): 1) (s) sham; 2) (h) hemorrhage (20% blood loss); 3)(sl-name) sham + pretreatment with l-name; and 4)(hl-name) hemorrhage and pretreatment with l-name. animals were sacrificed by decapitation 60 and 120 min after bleeding, and their hearts were extracted. results blood loss increased histochemical nos activity in a and v at 60 and 120 min (a 8% and 24%; v 21% and 45%, respectively). inducible anti-nos antibody western blot analysis showed increased protein in a and v 120 min after blood loss (654±13 and 465±9 arbitrary units, respectively). a and v endothelial nos expression increased at 60 min (18% and 147%, respectively) compared to s, showing a normal value 120 min after blood loss. conclusion the hypovolemic state induced by a 20% loss of total blood volume is associated with an heterogeneous and dynamic regulatory pattern of the activity and expression of nos in heart tissue.