Physiol. Res. 53: 439-447, 2004


Effects of Exogenous Donor of Nitric Oxide - Sodium Nitroprusside on Energy Production of Rat Reticulocytes

S. D. MALETIĆ, L. M. DRAGIĆEVIĆ-DJOKOVIĆ1, B. I. OGNJANOVIĆ,
R. V. ŽIKIĆ, A. Š. ŠTAJN, M. B. SPASIĆ2

Institute of Biology, Faculty of Sciences, 1Institute of Physiology, Faculty of Medicine, University of Kragujevac, Kragujevac and 2Institute for Biological Research “Siniša Stanković”, Department of Physiology, Belgrade, Serbia and Montenegro

Received April 22, 2003
AcceptedAugust 24, 2003



Summary
The effects of the sodium nitroprusside (SNP), a nitric oxide (NO) donor clinically used in the treatment of hypertensive emergencies on the energy production of rat reticulocytes were investigated. Rat reticulocyte-rich red blood cell suspensions were aerobically incubated without (control) or in the presence of different concentrations of SNP (0.1, 0.25, 0.5, 1.0 mM). SNP decreased total and coupled, but increased uncoupled oxygen consumption. This was accompanied by the stimulation of glycolysis, as measured by increased glucose consumption and lactate accumulation. Levels of all glycolytic intermediates indicate stimulation of hexokinase-phosphofructo kinase (HK-PFK), glyceraldehyde 3-phosphate dehydrogenase (GAPD) and pyruvate kinase (PK) activities in the presence of SNP. Due to the decrease of coupled oxygen consumption in the presence of SNP, ATP production via oxidative phosphorylation was significantly diminished. Simultaneous increase of glycolytic ATP production was not enough to provide constant ATP production. In addition, SNP significantly decreased ATP level, which was accompanied with increased ADP and AMP levels. However, the level of total adenine nucleotides was significantly lower, which was the consequence of increased catabolism of adenine nucleotides (increased hypoxanthine level). ATP/ADP ratio and adenylate energy charge level were significantly decreased. In conclusion, SNP induced inhibition of oxidative phosphorylation, stimulation of glycolysis, but depletion of total energy production in rat reticulocytes. These alterations were accompanied with instability of energy status.


Key words
Rat reticulocytes • Energy production • Energy status • Sodium nitroprusside • Nitric oxide


© 2004 by the Institute of Physiology, Czech Academy of Sciences