DISTRIBUTION OF IRON IN PLASMA OF ENDOTOXEMIC RATS.

GALLEANO M.; ROBELLO E.; PUNTARULO S.

Montevideo, Uruguay

Congreso; V Meeting of SFRBM-South America Group; 2007

SFRBM-South America Group

DISTRIBUTION OF IRON IN PLASMA OF ENDOTOXEMIC RATS. Galleano M., Robello E. and Puntarulo S. Physical Chemistry-PRALIB, School of Pharmacy and Biochemistry, University of Buenos Aires. Junín 956, C1113AAD, Buenos Aires, Argentina. The aim of this work was to study the role of nitric oxide (NO) on Fe distribution in plasma employing a model of endotoxemia. Female Sprague Dawley rats were administered with either lipopolysaccharide from Escherichia coli (serotype 0127:B8) (ip 4 mg/kg) (LPS), saline solution (C), L-NAME (ip 50 mg/kg) (L-NAME), or L-NAME simultaneously with LPS (L-NAME+LPS), and blood samples were obtained after 6h.  NO production was followed by measuring NO-Hb in blood by EPR at 77 K. LPS administration increased NO-Hb detection by 10 times as compared to C group. Both, the Fe content (39±3 mM vs. 14±1 mM, p<0.001, for C and LPS, respectively) and the total Fe binding capacity (TIBC) (149±5 mM vs. 85±21 mM, p<0.01, for C and LPS, respectively) were significantly decreased after LPS supplementation. The labile iron pool (LIP), measured in filtrated plasma by the fluorescent sensor calcein,  was not affected by the treatment (0.9±0.1 mM vs. 0.9±0.2 mM, for C and LPS, respectively). L-NAME administration in C group increased significantly the LIP values (2.3±0.3 mM vs. 0.9±0.1 mM, p<0.01, for L-NAME and C, respectively). Further studies will be required to clarified the mechanism/s involved in this effect. Since L-NAME is a known NOS inhibitor, the administration of LPS in L-NAME treated animals led to a lower content of NO detected in plasma respect to the non L-NAME treated rats (7±3 AU vs. 22±0.7 AU, p<0.05, L-NAME+LPS and LPS, respectively). In the presence of L-NAME, LPS supplementation decreased Fe content in plasma (51±4 mM vs. 27±24 mM, p< 0.05, for L-NAME and L-NAME+LPS respectively) as it did in C group. Moreover, LIP level was restored to its control value (0.9±0.2 mM) after the simultaneous supplementation of L-NAME and LPS. These results suggest that the decrease in the content of Fe in plasma would be independent of the steady state concentration of NO and that LIP is not affected by LPS administration in control animals, limiting the damaging effects of catalytic active Fe. Supported by University of Buenos Aires, ANPCYT and CONICET.