Mechanical properties of the mammalian vas deferens. II. In the active state.

The mechanical response of the vas induced by field stimulation is described in this paper. The experiments were performed, in vitro, on vasa from Sprague-Dawley albino rats. In the maintained ac tetanic stimulation, the active force achieves the peak magnitude in about 1 to 1.2 sec; thereafter, it relaxes gradually. For a given stimulus voltage (amplitude), a maximal response is elicited at 60 Hz. At 6000 Hz, and greater, no response is elicited. The ability to respond to stimulus dies out in 2 hr at 5 degrees C above the normal temperature of 37 degrees C; the ability to respond to stimulus remains unaffected at 5 degrees C below the normal temperature. The active force is always larger than the passive force when the vas is subjected to titanic stimulation near its in situ length.