OBJECTIVETo study the biological activities of several alpha1-adrenoceptor antagonists in vitro.

METHODSThe anococcygeal muscle from male Sprague-Dawley rats (300-350 g) was isolated, removed and suspended in a 20-ml organ chamber containing Krebs solution at 37 degrees C, pH 7.4. The muscle preparations were set at a resting tension of 1.0 g and allowed to equilibrate for 1 h in the Krebs solution. After thorough washing, the anococcygeal muscle preparations were examined for the effects of the tested compounds with increased concentrations on its contractile/relaxant responses and the pA2 of antagonistic activity was assessed.

RESULTSSome of the target compounds displayed blocking activity to alpha1-adrenoceptor.

CONCLUSIONCompounds WB IV-1 and WB IV-3 showed good inhibiting activity, and were worth further studying.