Nitric oxide, superoxide anion and hydrogen peroxide production during heparin-induced capacitation cryopreserved bovine spermatozoa.

RODRIGUEZ PC; VALDEZ LB,; ZAOBORNYJ T; BOVERIS A; BECONI MT

Santiago

Congreso; Free Radicals and Antioxidants in Chile 2009: VI Meeting of the Society for Free Radical Biology and Medicine, South American Group; 2009

International Society for Free Radical Biology and Medicine

The aim of this work was to quantify the endogenous NO, 02' and ONOOproductionduring heparin-induced capacitation of cryopreserved bovinesperrnatozoa. Oxygen uptake, NO and 02' production, and capacitation wereevaluated at different times in sperrnatezoa incubated for 45 min at 38°C: a) withheparin (la VI/mI), b) with heparin (la VI/mI) + L-NAME(500pM) or DPI (2pM) and c) without heparin (control). A hyperbolic increase as a function of timewas observed for heparin-dependent capacitation, 02 uptake, and NO production.Converse!y,°2' production was increased during the first 15 min of incubation,showing a decrease from this time until 45 minoAt 15 min of heparin incubation,a three-fold increase in 02 consumption (5.9 :1:0.6 nmoI/min.107 ce!ls), anenhance in NO re!ease (1.7 :1:0.4 nmoVmin.107ce!ls), and a five-fold increasein °2' production (1.3 :1:0.07 nmoVmin.107ce!ls), respect te the non capacitatedsperrnatozoa, were observed. The addition of L-NAMEdecreased NO production(50%), while the addition of DPI decreased °2' production (80%). Peroxynitriteproduction at 15 min of sperm capacitation was calculated taking into accountNO and °2' generation and the second-order rate constant of the reaction betweenthese species (kl= 1.9 x 1010M,I 5.1).This value results about 1.7 nmoVmin.107ce!ls, indicating that NO concentration is limiting for ONOO- formation in theincubation medium. To conclude, heparin-induced capacitation of cryopreservedbovine sperrnatozoa enhances NO and °2' production, generating an increase inONOO' production.