Rhythmical oscillations in rat testicular microcirculation as recorded by laser Doppler flowmetry

Abstract

Local testicular blood flow, recorded by laser Doppler flowmetry, showed large oscillations with a frequency of 5-10 min-1. The recorded oscillations could represent mainly local microvascular blood flow variations rather than variations in total testicular blood flow or tissue movements. Blood flow simultaneously measured at 2 separate sites showed oscillations with different frequencies. A local subcapsular injection of room-tempered saline under 1 probe site eradicated oscillations under that probe, but not under another adjacent probe; when the testicular capsule was split open, recordings of blood flow continued to show oscillations. The amplitude of the oscillations was rather large (peak to peak value .apprx. 50% of mean flow value). No movements of the testicular surface were seen. A 20 min continuous infusion of 0.4 .mu.g/min noradrenaline [norepinephrine] did induce a decrease in plasma testosterone concentration, but did not change the mean blood flow. The oscillations nearly completely disappeared during the infusion period. Laser Doppler flowmetry is a versatile method; the rat testis provides a suitable organ in the study of the origin and functional importance of these oscillations.