The effects of iproniazid and reserpine on the accumulation of granular vesicles and noradrenaline in constricted adrenergic nerves

Abstract

. The accumulation of granular vesicles proximal to a constriction applied to hypogastric nerves has been investigated with the electron microscope in cats treated with reserpine and/or iproniazid. . The ultrastructural changes have been correlated with the accumulation of noradrenaline at the same site in similarly treated animals. . The findings give further support to the view that granular vesicles constitute a major storage site for intraneuronal noradrenaline.

Further evidence for the involvement of microtubules in the intra‐axonal movement of noradrenaline storage granules

“…After 48 hr incubation in vitro in the absence of colchicine the marked variation in the organelle content and in the degree of axonal swelling found in segment P 1 was similar to that seen in comparable experiments on hypogastric nerve ligated in vivo (see Kapeller & Mayor, 1969;Banks, Mangnall & Mayor, 1969). In longitudinal sections and in serial transverse sections considerable variation was seen along relatively short lengths of individual axons.…”

“…The view that noradrenaline storage vesicles can be equated with densecored vesicles receives confirmation from the finding that the reduction in the accumulation of noradrenaline caused by colchicine is paralleled by the reduction in the number of dense-cored vesicles accumulating above the ligature (see also Banks, Kapeller & Mayor, 1969).…”

Two populations or granular vesicles in constricted post‐ganglionic sympathetic nerves.

“…In all three cats which received reserpine the hypogastric nerve segment taken for assay contained less than 0-01 nmol noradrenaline. The 731 D. R. TOMLINSON treatment was therefore assumed to have produced a marked amine depletion since, in the absence of reserpine, about 0-8 nmol noradrenaline would have accumulated (Banks et al 1969). DISCUSSION The accumulation of large (60-90 nm diameter) granular vesicles proximal to constrictions applied to sympathetic post-ganglionic nerves is well reported Geffen & Ostberg, 1969).…”

“…The D. R. TOMLINSON treatment was therefore assumed to have produced a marked amine depletion since, in the absence of reserpine, about 0-8 nmol noradrenaline would have accumulated (Banks et al 1969).…”

“…These findings indicate that the majority of granular vesicles, irrespective of size, are involved in monamine storage. The work of Banks, Kapeller & Mayor (1969) indicates that the monoamine concerned is noradrenaline, although the lack of specificity of monoamine depletion by reserpine prevents conclusive interpretation. This suggestion is in accordance with the findings of Bisby & Fillenz (1971) who demonstrated by cell fractionation methods that both large and small granular vesicles from cat spleen store noradrenaline.…”