Nitric Oxide and Superoxide Anion Production During Heparin‐Induced Capacitation in Cryopreserved Bovine Spermatozoa |
| |
| Authors: | PC Rodriguez LB Valdez T Zaobornyj A Boveris MT Beconi |
| |
| Institution: | 1. Biological Chemistry, INITRA, School of Veterinary Science;2. Laboratory of Free Radical Biology (PRALIB‐CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina |
| |
| Abstract: | The aim of this work was to quantify NO, O2? and ONOO? production during heparin‐induced capacitation of cryopreserved bovine spermatozoa. A time dependent hyperbolic increase was observed for heparin‐dependent capacitation, O2 uptake, and NO production. Conversely, O2? production was increased during the first 15 min of incubation, showing a decrease from this time until 45 min. At 15 min of heparin incubation, a threefold increase in O2 consumption (5.9 ± 0.6 nmol/min × 107 cells), an enhancement in NO release (1.1 ± 0.2 nmol/min × 107 cells), and a five‐fold increase in O2? production (1.3 ± 0.07 nmol/min × 107 cells), were observed. Peroxynitrite production rate was estimated taking into account NO and O2? generation and the second‐order rate constant of the reaction between these species. To conclude, heparin‐induced capacitation of cryopreserved bovine spermatozoa activates (i) mitochondrial O2 uptake by high ADP levels due to increased energy requirements, (ii) NO production by a constitutive NOS and (iii) O2? production by a membrane‐bound NAD(P)H oxidase. The products of both enzymes are released to the extracellular space and could be involved in the process of sperm capacitation. |
| |
| Keywords: | |
|
|
