Differential effects of inhibitors of monoamine oxidase types A and B on the adrenergic system of the rabbit iris

Topical installation of inhibitors of monoamine oxidase types A or B into the rabbit eye, followed by the administration of a releaser of monoamines (Ro 4 1284), induces strong and sustained dilation of the iris. The mydriatic pattern differs markedly with A and B inhibitors and with the duration of the inhibitor treatment. The type B inhibitor, deprenyl, prevents the degradation of exogenous 2 phenylethylamine and possibly of the endogenous amine X capable of releasing monoamines from a compartment less accessible to Ro 4 1284.