Real-time monitoring of nitric oxide and blood flow during ischemia-reperfusion in the rat testis

Abstract

In the present study, we attempted to clarify the role of nitric oxide (NO) and its release during the ischemia-reperfusion rat testis. Eight-week-old male Sprague-Dawley rats were divided into seven groups: age-matched control rats, ischemia (30 minutes)-reperfusion (30 minutes) rats without N^G-nitro-L-arginine methyl ester (L-NAME) and L-arginine (L-Arg) treatment, ischemia (30 minutes)-reperfusion (30 minutes) rats treated with L-NAME (10, 30, and 100 mg/kg), ischemia-reperfusion rats treated with L-Arg (10 and 30 mg/kg). Sixty minutes prior to induction of ischemia, L-NAME or L-Arg was administrated intraperitoneally. Real-time monitoring of blood flow and NO release were measured simultaneously with a laser Doppler flowmeter and an NO-selective electrode, respectively. NO₂-NO₃ and malonaldehyde (MDA) concentrations were measured in the experimental testes. Furthermore, we investigated possible morphological changes in the testis. Clamping of the testicular artery decreased blood flow to 5–20% of the basal level measured before clamping. Immediately following clipping of the artery, NO release rapidly increased. After removing the clip, NO release gradually returned to the basal level. This phenomenon was enhanced by treatment with L-Arg and inhibited by treatment with L-NAME. NO₂-NO₃ concentrations were increased by treatment with L-Arg and decreased by treatment with L-NAME, while MDA concentrations were increased by treatment with L-NAME and were decreased by treatment with L-Arg. In histological studies, the ischemia-reperfusion caused infiltration of leukocytes and a rupture of microvessels in the testis. Our data suggest that NO has cytoprotective effects on ischemia-reperfusion injury in the rat testis.