Nitric oxide production and mitochondrial dysfunction during rat thymocyte apoptosis.
Production of nitric oxide (NO) by mitochondrial membranes as methemoglobin formation sensitive to N(G)-methyl-l-arginine inhibition and mitochondrial O(2) consumption in metabolic states 3 and 4 and the respiratory control (state 3/state 4) were measured at early stages of rat thymocyte apoptosis. Programmed cell death was induced by addition of methylprednisolone and etoposide to thymocyte suspensions. Increased NO production by mitochondrial membranes was observed after 30 min of methylprednisolone and etoposide addition and was accompanied by mitochondrial respiratory impairment as an early phenomenon in apoptotic thymocytes. The respiratory control in isolated mitochondria from untreated thymocytes was 4.2 +/- 0.2 and decreased to 3.1 +/- 0.2 and 1.9 +/- 0.3 after 1 h of methylprednisolone and etoposide treatment, respectively. The low mitochondrial respiratory control was accompanied by a marked decrease in GSH and cytochrome c content. Moreover, an inhibitory effect in the amount of apoptosis due to thymocyte pretreatment with N(G)-methyl-l-arginine and N(omega)-nitro-(l)-arginine (l-NNA), indicate that nitric oxide production is closely involved in the signaling of rat thymocyte apoptosis.
Bustamante
J
J
Laboratory of Free Radical Biology, School of Pharmacy and Biochemistry, University of Buenos Aires, Junin 956, Buenos Aires, 1113, Argentina. juanitab@ffyb.uba.ar
Bersier
G
G
Romero
M
M
Badin
R A
RA
Boveris
A
A
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019069:Cell Respiration / Q000187:drug effects; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D005047:Etoposide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008775:Methylprednisolone / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D010085:Oxidative Phosphorylation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D019323:omega-N-Methylarginine / Q000494:pharmacology
D003574:Cytochrome c Group; D019335:Nitroarginine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D005047:Etoposide; D019001:Nitric Oxide Synthase; D005978:Glutathione; D008775:Methylprednisolone