Interaction of desipramine and ciclazindol with adrenergic mechanisms in the human iris [proceedings]

a-Methylnoradrenaline (MNA) and phenylephrine (PE) possess predominantly pre-and post-synaptic a agonist properties in vitro (Langer, 1979).An im- proved index of the rate of release of noradrenaline (NAR) may be obtained by correcting endogenous plasma noradrenaline (NA) for individual values of clearance (Fitzgerald, Hossmann, Hamilton, Reid, Davies & Dollery, 1979).We have studied the effect of infusions of MNA and PE on NAR in man.MNA, PE and saline placebo were each infused whilst the subjects spent 10 min supine and 5 min sitting, standing and submaximally exercising.The infusions were performed at subpressor and mildly pressor rates of MNA; A systolic BP + (5.65 + 0.8 mm Hg) and PE + (5.82 + 0.76 mm Hg).Plasma NA was measured radioenzymatically (Henry, Starman, Johnson & Williams, 1975).Clearance was derived from steady state plasma concentrations during an hour long infusion of (-Y)NA (0.05 ,ug kg-' min 1).