Effect of terodiline on isolated rabbit and guinea pig detrusor was investigated in comparison with that of flavoxate and oxybutynin. Terodiline (10(-6) M) parallelly shifted the dose-response curve for carbachol in rabbit detrusor to the right, and high doses of terodiline (3 X 10(-6)-3 X 10(-5) M) inhibited the maximal contraction. Flavoxate (10(-5) M or more) also inhibited the maximal contraction. Oxybutynin (10(-8) M or more) shifted the dose-response curve to the right, but did not affect the maximal contraction. At 3 X 10(-6) M or more, terodiline dose-dependently inhibited the Ca-contraction of rabbit detrusor. While the contraction of rabbit detrusor induced by electrical field stimulation was inhibited by atropine (3 X 10(-7) M) or nifedipine (3 X 10(-6) M) by 35% or 73%, respectively, the combination of atropine (10(-7) M) and nifedipine (10(-6) M) abolished it. Oxybutynin (3 X 10(-7) M) inhibited it by about 30%; terodiline (10(-6) M or more) and flavoxate (10(-5) M or more) dose-dependently inhibited it, and abolished at 10(-4) M and 3 X 10(-4) M, respectively. Terodiline inhibited the 1-quinuclidinyl-[phenyl-4-3H]-benzilate binding to the microsomal fraction of guinea pig urinary bladder, brain, atria and ileum dose-dependently, and it had similar affinity among these fractions. Terodiline (3 X 10(-6) M or more) inhibited the 45Ca uptake to minced guinea pig urinary bladder dose-dependently, but did not influence the 45Ca efflux even at 10(-4) M. Flavoxate (10(-4) M) only slightly inhibited the 45Ca uptake.(ABSTRACT TRUNCATED AT 250 WORDS)