The contraction induced by ethylenediaminetetracetic acid-4 sodium (EDTA-4Na) in guinea-pig isolated vas deferens kept in isotonic sucrose medium.

1. Ethylenediaminetetracetic acid--4 sodium (EDTA--4Na) induced a contraction in guinea-pig isolated vas deferens kept in isotonic sucrose medium containing 0.07% Nahco3 and 0.1% glucose after preincubation in Locke's solution. The maximum contraction was 82.1 +/- 6.7% of that induced by added KCl. 2. EDTA--Ca--2Na (10(-7) to 10(-3) g/ml) induced no contraction in preparations kept in the sucrose medium. 3. The EDTA--4Na-induced contraction was also obtained when sucrose in the sucrose medium was replaced by glucose but not when the preparation was kept in Locke's solution. 4. The EDTA--4Na-induced contraction was decreased by reduction of the CaCl2 of KCl concentration of the Locke's solution in which the preparation had been preincubated before placing in the sucrose medium. 5. The EDTA--4Na-induced contraction was suppressed with increasing concentrations of NaCl used to partially replace sucrose in the sucrose medium. 6. When the preparation was kept in EDTA-free sucrose medium after pretreatment with 10(-4) g/ml of EDTA--4Na in the sucrose medium for 20 min, a contraction was induced by added CaCl2. The maximum contraction induced by CaCl2 was 30.1 +/- 11.8% of that of the EDTA--4Na-induced contraction, when CaCl2 was added at 20 min after the exchange of medium.