Abstract

FELLET, Andrea L. et al. Hypovolemic State Modulates Nitric Oxide Synthase Activity and Expression in the Cardiovascular System. Rev. argent. cardiol. [online]. 2006, vol.74, n.1, pp.43-49. ISSN 1850-3748.

Background We have previously demonstrated that pre-treatment with the nitric oxide synthase (NOS) inhibitor N^G-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.

Keywords : Hemorrhage; Nitric oxide synthase; Hypotension; Heart rate.

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