The effects of lithium, indomethacin, and neomycin on vasopressin-induced contractions in rat urinary bladder.

1. [Arg8]Vasopressin (AVP) induced a contraction response in rat urinary bladder smooth muscle in a dose-dependent manner. 2. Indomethacin in a 10-microM concentration cannot change the effects of AVP on urinary bladder smooth muscle, which seem to be mediated by a direct action on the muscle rather than indirectly through prostanoid release. 3. Lithium (0.5, 1, and 10 mM) made the muscle more sensitive to AVP action. 4. Neomycin (1.25, 2.5, and 5 mM) had an inhibitory effect on AVP-induced contraction. 5. It seems that in rat urinary bladder vasopressin-induced contraction is mediated through phosphoinositide metabolism.