The effect of temperature on the potential difference and input resistance of rat seminiferous tubules

1. The p.d. of rat seminiferous tubules was 5.86 +/- 0.15 mV, lumen negative, at 33 degrees C and varied linearly with temperature between 24 and 37 degrees C, exhibiting an apparent Q(10) (25-35 degrees C) of 2.0 with a slope of 0.43 mV/ degrees C. Exposing testes to a temperature of 37-43 degrees C resulted in an initial hyperpolarization followed by depolarization of the tubules. These changes were more rapid in testes exposed to 41-43 degrees C than in testes exposed to 37-39 degrees C.2. The R(in) of seminiferous tubules was 198 +/- 7.8 kOmega at a testis temperature of 33 degrees C. The R(in) decreased when testes were maintained at 37 and 41 degrees C, the rate of decrease being similar to the rate of depolarization.3. Exposing testes to deep body temperature by unilateral surgical cryptorchidism caused a reduction of 30 and 64% in tubular p.d. and R(in) respectively when measured 24 hr after surgery. Exposure to deep body temperature for up to 4 days did not cause any further change in either parameter.4. There was no evidence that lanthanum penetrated through the Sertoli cell tight junctions after exposing testes to 41 degrees C for up to 30 min.5. The results indicate that the seminiferous tubule p.d. is maintained by a temperature-sensitive, cellular mechanism. Exposing testes to deep body temperature or above depolarized the tubules and increased their permeability.