EFFECTS OF VANADATE IN TESTICULAR CAPSULE OF THE RAT

1. The effects of sodium orthovanadate (vanadate, 10(-5) to 3 x 10(-4) M) on testicular capsule of the rat, and the modifications of these effects by the calcium chelator EGTA (2 mM), the calcium entry blockers verapamil (5 x 10(-5) M), nifedipine (10(-5) M), flunarizine (5 x 10(-5) M) and diltiazen (5 x 10(-5) M), the (Na+ + K+)-ATPase inhibitor ouabain, the Na+/Ca2+ exchange inhibitor amiloride, and the calmodulin antagonists trifluoperazine (10(-4) M) and W-7 (5 x 10(-5) M) have been studied. 2. Vanadate induced contraction of the rat testicular capsule in a dose-dependent way (ED50: 82.8 +/- 7.4 x 10(-6) M). 3. The contraction induced by vanadate (3 and 30 x 10(-5) M) were abolished by EGTA and not modified by verapamil, nifedipine, flunarizine or diltiazen. 4. Amiloride (1 and 5 x 10(-5) M), but not ouabain (5 x 10(-5) and 10(-4) M), inhibit in a dose-dependent way the contraction induced by two doses of vanadate (3 and 30 x 10(-5) M). 5. Trifluoperazine and W-7 significantly inhibit the contraction of testicular capsule to 3 and 30 x 10(-5) M vanadate.