Nitric oxide and superoxide anion production during heparin-induced capacitation in cryopreserved bovine spermatozoa.
The aim of this work was to quantify NO,O(2)(-) and ONOO(-) production during heparin-induced capacitation of cryopreserved bovine spermatozoa. A time dependent hyperbolic increase was observed for heparin-dependent capacitation, O(2) uptake, and NO production. Conversely, O(2)(-) 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 O(2) consumption (5.9 ± 0.6 nmol/min × 10(7) cells), an enhancement in NO release (1.1 ± 0.2 nmol/min × 10(7) cells), and a five-fold increase in O(2)(-) production (1.3 ± 0.07 nmol/min × 10(7) cells), were observed. Peroxynitrite production rate was estimated taking into account NO and O(2)(-) 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 O(2) uptake by high ADP levels due to increased energy requirements, (ii) NO production by a constitutive NOS and (iii) O(2)(-) 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.
Rodriguez
P C
PC
Biological Chemistry, INITRA, School of Veterinary Science, University of Buenos Aires, Buenos Aires, Argentina. prodriguez@fvet.uba.ar
Valdez
L B
LB
Zaobornyj
T
T
Boveris
A
A
Beconi
M T
MT
D000818:Animals; D002417:Cattle; D015925:Cryopreservation / Q000662:veterinary; D006493:Heparin / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D010101:Oxygen Consumption; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013075:Sperm Capacitation / Q000187:drug effects / Q000502:physiology*; D013081:Sperm Motility / Q000502:physiology; D013481:Superoxides / Q000378:metabolism*
D013481:Superoxides; D009569:Nitric Oxide; D006493:Heparin