The blood-testis barrier and temperature damage to the testis of the rat.

The integrity of the blood-testis barrier was investigated during and after local heating of rat testes sufficient to produce a temporary cessation of spermatogenesis. The flow, ionic composition and protein content of rete testis fluid (RTF) collected from testes maintained at 33 or 41 degrees C were unaffected either at the time of treatment or up to 2 days later when the major cytological consequences of heating occurred. The normally low rate of transfer of albumin from blood to RTF was unaffected during and after heating. Transfer constants for radioactive K, Rb, Na and lysine consistently increased during heating although there were time-dependent differences between the patterns of response for each molecule. The normally rapid transfer of testosterone was unaffected by heating, but the entry rates of radioactivity into RTF after the infusion of more slowly diffusing steroids were enhanced at 41 degrees C. The clearest effects of heating were an approximate doubling in the uptake of oxygen and decrease in the net synthesis of protein by the testis. It is concluded that heating sufficient to damage spermatogenesis was not associated with dramatic alterations in the integrity of the blood-testis barrier but more with changes in testicular metabolism.