Intraneuronal and extraneuronal accumulation of sympathomimetic amines in the isolated nictitating membrane of the cat.

摘要: The accumulation of norepinephrine-H 3 (NE-H ) in the isolated normal nictitating membrane cat was linearly related to bath concentrations which varied from 0.6 ng/ml 100 µg/mi dl -NE-H . Experiments with denervated membranes showed that low mainly due intraneuronal accumulation, while extraneuronal occurred both and when concentration increased 1 µg/ml or more If it is assumed identical membranes, can be calculated as difference NE-H content between membrane. Intraneuronal saturable at about sharp increase observed higher coincided a pronounced relative decrease tissue 0-methylated metabolites-H Intraneuronally retained had long half-life on wash out, extraneuronally only 10 minutes. At least some norepinephrine leaves stores seems able reach receptors. two types were characterized pharmacologically. reduced by cocaine, phenoxybenzamine pretreatment reserpine not affected metanephrine, block catechol-O-methyltransferase monoamine oxidase. Extraneuronal metanephrine phenoxybenzamine, after oxidase unaffected cocaine reaerpine. Relative rates were: isoproterenol-H > epinephrine-H =