Figure 5.

The administration of rt-PA restores the contractile response of vasa deferentia isolated from mice lacking t-PA. (A) Contractile responses (both purinergic and adrenergic) of vasa deferentia isolated from WT mice to EFS (30 Hz, supramaximal voltage; duration of 15 s at 5-min intervals, with pulses of 1 ms) either in the absence or presence of 0.6 and 1 μg/ml rt-PA (15-min incubation). The 0.6-μg/ml concentration was ineffective, whereas at 1 μg/ml, rt-PA potentiated both the purinergic and adrenergic responses by ∼70 and ∼50%, respectively (*, P < 0.05). Bars represent the mean contractile response amplitude, which is expressed as a percentage of the response to 80 mM K⁺ (± SE [error bars]; n = 4–8). (B) Frequency response curves for the contractile response of vasa deferentia to EFS (0–32 Hz, supramaximal voltage; for 1 ms every 15 s). Vasa were isolated from t-PA^−/− mice and from their WT controls. Incubation of vasa from t-PA^−/− mice with rt-PA (at the subthreshold concentration of 0.6 μg/ml for 15 min) restored the depressed contractile response to EFS to the same magnitude as in vasa from control mice. Points are means (± SE; n = 8 and 4 for WT and t-PA^−/−, respectively) of maximal contractile amplitudes expressed as percentages of the response to 80 mM K⁺. Arrows indicate the upward shifts elicited by the administration of rt-PA in vasa deferentia isolated from animals deprived of t-PA.