TESTICULAR MICROVASCULAR BLOOD-FLOW - ALTERATION AFTER LEYDIG-CELL ERADICATION AND ISCHEMIA BUT NOT EXPERIMENTAL VARICOCELE

Testicular microvascular blood flow is known to exhibit vasomotion, or pulsatile flow. In the present study we have used laser-Doppler flowm etry to study microvascular blood flow in the rat testis and to examin e the response of the microvasculature to pharmacological stimulation and pathophysiological conditions. With a mean microvascular flow rate of 13.3 +/- 1.7 perfusion units (PU), the mean cycle amplitude was 3. 4 +/- 0.6 PU, and the cycle frequency was 10.3 +/- 0.8 cycles per minu te. Blood flow parameters did not differ between left and right testes , between scrotal testes and testes in a 35 degrees C glass testicle r eceptacle, or among testicular regions. Perifusion of seminiferous tub ules and their vasculature with 0.1 mu g/mu l epinephrine significantl y reduced microvascular blood flow and eliminated vasomotion. Eliminat ion of Leydig cells and intratesticular testosterone also eliminated v asomotion but did not significantly alter mean blood flow rates. Thirt y days after imposition of experimental left varicocele (ELV) there we re no significant changes in microvascular blood flow parameters. Test icular torsion of sufficient degree and duration to destroy spermatoge nesis did not induce a change in mean microvascular blood flow rate 24 hours after repair of torsion, but testicular vasomotion was eliminat ed in the majority of animals. We conclude that microvascular flow is altered in some testicular pathologies and not in others. The mechanis ms underlying changes in microvascular blood flow are at present unkno wn.