Metabolism of sodium nitroprusside (SNP) in rat red blood cells

Sodium nitroprusside (SNP) is an established drug, clinically used in the treatment of hypertensive emergencies. The aim of this study is further elucidation of the molecular mechanism of the SNP action, particularly its metabolism in rat erythrocytes and reticulocytes. Rats erythrocyte and reticulocyte-rich suspensions were aerobically incubated without (control) or in the presence of SNP (0.1,0.25,0.5,1.0 and 1.5 mM). The concentrations of reactive nitrogen species (RNS) and reactive oxygen species (ROS) were determined after incubation. In rat erythrocytes, SNP did not alter nitrite level (NO+ ion indicator), while significantly increased concentrations of hydroxylamine (NO- ion indicator), S-nitrosothiols (SNO) and 3-nitrotyrosine (peroxynitrite indicator). Concentration of superoxide anion (O2-) decreased in the presence of low doses of SNP only, while level of hydrogen peroxide (H2O2) increased in dose-dependent manner in rat erythrocytes. On the other hand, SNP significantly increased nitrite, hydroxylamine and 3-nitrotyrosine concentrations in rat reticulocytes. In addition, low doses of SNP induced decrease of O2- level. Concentration of H2O2 did not alter in rat reticulocytes. On the basis of these data, we can conclude: SNP spontaneously liberated nitric oxide as NO- ion in rat erythrocytes and reticulocytes. In addition, applied experimental doses of SNP induced strong nitrosative and oxidative stress in these cells.Natrijum nitroprusid (SNP) je lek koji se klinički koristi u tretmanu hipertenzija. Cilj ovog rada je da se objasne molekularni mehanizmi delovanja SNPa, sa posebnim akcentom na metabolizam ovog leka u eritrocitima i retikulocitima pacova. Suspenzije eritrocita i crvenih krvnih ćelija bogate retikulocitima su aerobno inkubirane bez (kontrola) ili u prisustvu različitih koncentracija SNPa (0.1, 0.25, 0.5, 1.0 i 1.5 mM). Koncentracije reaktivnih vrsta azota (RNS) i kiseonika (ROS) su određivane nakon inkubacije. U eritrocitima pacova, SNP ne menja koncentraciju nitrita (indikator NO+ jona), dok značajno povećava koncentracije hidroksilamina (indicator NO- jona), S-nitrozotiola (SNO) and 3-nitrotirozina (indikator peroksinitrita). Koncentracija superoksid anjon radikala (O2-) je smanjena samo u prisustvu niskih doza SNP, dok je nivo vodonik peroksida (H2O2) povećan na dozno-zavisan način u eritrocitima pacova. S druge strane, SNP značajno povećava koncentracije nitrita, hidroksilamina i 3-nitrotirozina u retikulocitima pacova. Niske doze SNPa indukuju smanjenje O2- nivoa. Koncentracije H2O2 nisu promenjenje u retikulocitima pacova. Na osnovu iznetih podataka, možemo zaključiti: SNP spontano oslobađa azot monoksid kao NO" jon u eritrocitima i retikulocitima pacova. Primenjene eksperimentalne doze SNPa indukuju snažan nitrozacioni i oksidacioni stres u ovim ćelijama.nul