Contractile response and electrophysiological properties in enzymatically dispersed smooth muscle cells of rat vas deferens.

Electrophysiological studies were performed on single smooth muscle cells isolated from the vas deferens of the rat. The tissue was preincubated in Ca-free modified Tyrode's solution for 1 h and then transferred to a high-K solution for 1 h. It was next minced and treated with the enzyme solution composed of 600-800 unit/ml collagenase and 40 unit/ml elastase. The procedure yielded about 50% spindle shaped Ca-tolerant cells (100-250 microns in length and about 10 microns in diameter). These cells could contract during the superfusion with the solutions containing 10(-8) to 10(-3) M norepinephrine (NE) or adenosine triphosphate (ATP). The cells isolated from the epididymal portion were more sensitive to norepinephrine than were those from the prostatic part. Their basic electrical properties were studied using tight-seal suction electrode technique. The cells had resting potentials around -40 mV and their input resistance was about 0.8 G omega. Action potentials could be evoked by application of depolarizing current. During whole cell voltage clamp, an inward current followed by an outward current was recorded when 800 ms pulses from a holding potential of -60 mV to test potentials positive than -40 mV were applied. The transient outward current generally recorded in other smooth muscle cells was not seen in these cells. The amplitude of the inward current was Ca dependent and sensitive to a Ca antagonist, nicardipine, indicating that Ca ion is the main carrier of this component of the current. When the pipette was filled with Cs-containing solution, the outward current was abolished.(ABSTRACT TRUNCATED AT 250 WORDS)