The effects of iprindole on noradrenergic transmission in the rat anococcygeus muscle.

The effects of iprindole on the contractile responses to field stimulation and to exogenously applied agents have been studied in the rat anococcygeus muscle. In addition the effects on the spontaneous overflow of 3H and that induced by field stimulation (following preloading of the tissue with [3H]-noradrenaline) are reported. Iprindole (10(-7)-5 X 10(-6) M) had no effect on the contractile responses to acetylcholine. Iprindole at 10(-7) or 10(-6) M was equieffective in potentiating the contractile responses to either field stimulation or to noradrenaline. With a higher concentration of iprindole (5 X 10(-6) M) the potentiation was greater. The responses to oxymetazoline were potentiated and inhibited by iprindole at 10(-8) and 10(-7) M, respectively. Iprindole at 10(-6) M potentiated the responses to tyramine. The effects of iprindole at 10(-7) and 5 X 10(-6) M on the responses to field stimulation and to noradrenaline were not altered by the presence of ouabain (5 X 10(-5) M), neostigmine (10(-6) M) or yohimbine (10(-7) M). In the presence of desipramine (10(-6) M), iprindole at 10(-7) M potentiated the contractile responses to field stimulation and to noradrenaline. The higher concentrations of iprindole (10(-6) and 5 X 10(-6) M) inhibited the contractile responses to field stimulation and to noradrenaline in the presence of desipramine. Iprindole (10(-7) M) had no effect on the relaxant responses to field stimulation. Iprindole at 10(-7) or 10(-6) M had no effect on the spontaneous overflow of 3H or that induced by field stimulation at 2 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)