Factors affecting the extraneuronal inactivation of noradrenaline in cardiac and smooth muscle.

Abstract

1. The relation between density of adrenergic innervation, noradrenaline (NA) accumulation (as seen with the fluorescence histochemical method) in tissues incubated in a high concentration of NA, and monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT) activities, were examined in a wide range of tissues from different species.2. Evidence was obtained to support the proposal that accumulation of NA in the non-innervated smooth muscle of the human umbilical artery and chick amnion is associated with very low activities of COMT within muscle cells.3. The wide variation in tissue accumulation of NA in adrenergically innervated muscles was confirmed. For example, in the rabbit atrium..