Effect of the Adrenergic Neurone Blocker, β-TM 10, on the Depletion of Noradrenaline induced by Denervation or Reserpine
The noradrenaline content of the rat submaxillary gland was determined fluorimetrically as various times after sympathetic denervation as well as after the subcutaneous injection of reserpine (300 μg/kg). The effect of an adrenergic neurone blocker (β-TMIO) was compared with that of an inhibitor of monoamine oxidase (pargyline).
Both βTMIO (50 mg/kg s.c. given 6 hours and repeated 12 hours after the operation) and pargyline (100 mg/kg i.p. at the operation) delayed the decline of endogenous noradrenaline observed after denervation; the delay was similar for both treatments.
Both, β-TMIO (50 mg/kg s.c. 2 hours before reserpine) and pargyline (100 mg/ kg s.c. 6 hours before reserpine), caused a similar delay in the reserpine-induced decline of endogenous noradrenaline in the sympathetically decentralized gland.
Reserpine induced a higher rate of depletion in normal than in decentralized glands of untreated or pargyline-pretreated rats. However, the relation of depletion rates was reversed after β-TMIO.
It is concluded that the last mentioned effect is at least partly due to the adrenergic neurone blocking effect of β-TMIO. The antagonism by β-TMIO of the depleting effect of sympathetic denervation and of reserpine, on the other hand, is attributed to the ability of adrenergic neurone blocking agents to block monoamine oxidase. The results confirm earlier studies and indicate that the ability of adrenergic neurone blocking agents to block intraneuronal monoamine oxidase accounts for effects which up to now have been ascribed to their ability to prevent the release of noradrenaline by nerve impulses.
Key-Wordsβ-TM10 Adrenergic Neurone Blocker Sympathetic Denervation Noradrenaline Depletion by Reserpine Monoamine Oxidase Inhibition Pargyline
Unable to display preview. Download preview PDF.
- Callingham, B.A., Cass, R.: The effect of bretylium and cocaine on noradrenaline depletion. J. Pharmacol. exp. Ther. 14, 385–389 (1962).Google Scholar
- Crout, J.R.: Catechol amines in urine. In: Standard Methods of Clinical Chemistry, Vol. 3, pp. 62–80. Ed.: D. Seligson. New York: Academic Press 1961.Google Scholar
- Furchgott, R.F., Sanchez-Garcia, P.: Inhibition of monoamine oxidase of adrenergic nerve terminals by bretylium. Pharmacologist 8, 176 (1966).Google Scholar
- Noble, B.: Numerisches Rechnen, Bd. 88, S. 94–100. Mannheim: Bibl. Institut 1964.Google Scholar
- Nordenfeit, I.: Cholinesterase in the submaxillary gland of the rat after sympathetic denervation. Quart. J. Physiol. 53, 6–9 (1968).Google Scholar
- Pluchino, S., Orden III, L.S., van, Draskoczy, P.R., Langer, S.Z., Trendelenburg, IL: The effect of β-TM10 on the pharmacological, biochemical and morphological changes induced by denervation of the nictitating membrane of the cat. J. Pharmacol. exp. Ther. (in press).Google Scholar