PHARMACOLOGY OF THE ANTIHYPERTENSIVE GUANOXAN

[The "stimulatory proteodyschylia" in the amitriptylin (Laroxyl) treated rat parotid gland. Experiments on the effect of antidepressive pharmacotherapy on the parotid glands of the rat (author's transl)]

The activity of total amylase and isoamylases in the rat parotid gland is reduced by treatment with Amitriptylin (Laroxyl) for 3 and 7 days while the protein content of the glands remains constant. These changes are no longer visible after treatment for 21 days and following a period without drug application. To differentiate the disturbances of protein secretion (proteodyschylia) prominent in the clinical picture of sialadenosis, the following classification is proposed. We suggest the term "stimulatory proteodyschylia" for a decrease of acinar amylolytic activity, here caused by Amitriptylin application, as opposed to the "inhibitory proteodyschylia" characterized by an acinar amylase congestion.

The preparation and properties of (+)- and (--)-guanoxan

(±)-2-Aminomethyl-1, 4-benzodioxan has been resolved into its optically active isomers: (+)- and (-)-guanoxan have been synthesized from these. The pharmacological effects of racemic-guanoxan and of the two optical isomers have been compared on the isolated central ear artery of the rabbit, on the pithed rat in which pressor responses were evoked by stimulation of the thoraco-lumbar sympathetic outflow, and on the pre- and post-ganglionically stimulated nictitating membrane of the cat. The two isomers were equipotent in producing adrenergic neuron blockade. Initial catecholamine release was weak in the cat, but occurred more powerfully in the rabbit ear artery and in the rat. Ability to produce this effect resided mainly with the (+)-isomer. α-Adrenoreceptor blocking activity was detectable in the rat and was produced mainly by the (+)-isomer suggesting that its stereochemical configuration corresponds to that of D-(-)-noradrenaline. Ganglion blockade was an unimportant action of the compounds, but both isomers possessed weak atropine-like activity in the rat.

The effects of bretylium on C fibre excitation and noradrenaline release by acetylcholine and electrical stimulation

1. The effects of bretylium on the excitation of postganglionic adrenergic C fibres by acetylcholine and the release of noradrenaline by acetylcholine and electrical stimulation of the splenic nerves have been studied using the in situ and cross perfused cat spleen.2. Close arterial injections of acetylcholine (10-200 mug) evoked a brisk asynchronous discharge in fine filaments of the splenic nerve which reduced the height of the orthodromic C fibre compound action potential.3. Hexamethonium abolished both the excitation of C fibres and release of noradrenaline by acetylcholine, whereas the liberation of noradrenaline by electrical stimulation of the splenic nerves remained unchanged.4. Bretylium (0.5 and 1.0 mg) given close arterially blocked the output of noradrenaline and contractions of the spleen that occurred in response to nerve stimulation (30 c/s) but had much less effect on the responses to acetylcholine.5. Bretylium (2-4 mg) given close arterially blocked the output of noradrenaline and contractions of the spleen caused by both nerve stimulation (30 c/s) and acetylcholine.6. The close arterial injection of (+)-amphetamine sulphate (100 mug) after bretylium (2-4 mg) partially restored the output of noradrenaline and contractions of the spleen to both nerve stimulation and acetylcholine.7. The difference in the sensitivity to blockade by bretylium of the effects of nerve stimulation and the sympathomimetic effects of acetylcholine did not exist if the more "physiological" frequency of stimulation of 10 c/s was employed.8. The close arterial injection of acetylcholine (100 mug) caused a mean average fibre discharge frequency of 5.4 spikes/sec.9. Bretylium in amounts sufficient to completely block the sympathomimetic effects of acetylcholine did not alter the excitation of C fibres by acetylcholine.10. The significance of these results is discussed both in relation to the mode of action of bretylium and to the use of these differential effects of bretylium as evidence for the "cholinergic link" hypothesis.