Increased testicular blood flow maintains oxygen delivery and avoids testicular hypoxia in response to reduced oxygen content in inspired air

Despite a long-standing assertion that mammalian testes operate near hypoxia and increased testicular temperature causes frank hypoxia, we have preliminary evidence that changes are due to hyperthermia per se . The objective was to determine how variations in inspired oxygen concentration affected testicular blood flow, oxygen delivery and extraction, testicular temperature and lactate production. Eight rams were maintained under general anesthesia, with successive decreases in oxygen concentration in inspired air (100, 21 and 13%, respectively). As oxygen concentration decreased from 100 to 13%, there were increases in testicular blood flow (9.6 ± 1.7 vs 12.9 ± 1.9 ml/min/100 g of testis, P