ADRENERGIC RECEPTORS IN ISOLATED PERFUSED DOG SPLEEN

Experiments on the isolated perfused dog spleen in which the effect of intra-arterially injected catecholamines and splenic nerve stimulation were studied on vascular resistance, venous outflow and organ weight showed that (a) noradrenaline injection and splenic nerve stimulation provoked an increase in vascular resistance, whereas adrenaline injection was followed successively by a quick increase in perfusion pressure and a pronounced decrease of perfusion pressure, apparently due to a stimulation of vascular β-receptors, and then by a secondary increase in perfusion pressure, (b) the reduction of splenic weight was much less pronounced after noradrenaline injection than after adrenaline injection and splenic nerve stimulation, presumably due to a higher uptake of exogenous noradrenaline by the adrenergic nerve endings in the arterial wall, (c) direct evidence for the presence of vascular β-receptors was obtained by the injection of isoproterenol in isolated spleens maintained at a nearly physiological tone and by splenic nerve stimulation after a{script}-receptor blockade, and (d) the neurotransmitter released on splenic nerve stimulation was identified by paper chromatography as being predominantly noradrenaline together with small amounts of dopamine. © 1969.