The Uptake, Storage, Release and Metabolism of Noradrenaline in Sympathetic Nerves

Abstract

This chapter describes some investigations on the uptake, release, and metabolism of noradrenaline (NA) in sympathetic nerves. The main approach to study the biochemistry of adrenergic neurons is the use of adrenergic drugs and radioactive catecholamines. NA is metabolized via two major metabolic pathways: deamination by monoamine oxidase and O -methylation by catechol- O -methyltransferase. Radioactive NA is a useful tool to study the subcellular localization of NA in a sympathetic neuron. Endogenous NA is localized in a particulate component within splenic nerves. The uptake and binding of [ 3 H]noradrenaline by granulated vesicles of sympathetic nerves help in the temporary inactivation of a catecholamine. The storage of NA in a sympathetic neuron requires an optimal electrolyte milieu. The rate of NA synthesis varies with the rate of utilization of the catecholamine. NA is stored in sympathetic nerves in a heterogeneous fashion. It is also possible that O -methylation serves as a mechanism for the rapid removal of NA from the extraneural pool.