Splenic Nerve Research Articles

An electron microscopic study of the early changes distal to a constriction in sympathetic nerves.

The ultrastructural changes distal to a constriction in unmyelinated postganglionic sympathetic axons have been studied in the cat splenic and hypogastric nerves at intervals up to 24h after operation. Since the immediate postoperative changes were identical with those found proximal to the lesion it was concluded that they were due to the mechanical effects of tying the ligature. Within a few hours of operation there was an accumulation of organelles immediately distal to the constriction. At all times this was greatest within 0.5 mm of the lesion and only rarely extended beyond the first 1 mm even after 24h. The organelles which accumulated included mitochondria, many of which were swollen, pleomorphic myelin figures, multi-vesicular bodies, agranular vesicles and vacuoles of various sizes. Vesicles with an electron dense core, i.e. granular vesicles did not accumulate distal to the constriction. Further from the constriction focal accumulations of some structures, in particular mitochondria and myelin figures, did occur but they were rare. In this part of the nerve there was generally a diminution in the number of organelles, and a marked alteration in the axonal morphology. Alternating swollen and narrow regions were common, and many axons were very irregular as if ‘collapsing’. While filaments and occasionally fine tubules persisted in some of these axons up to 24h after operation, there was a reduction in the endoplasmic reticulum. These findings are compared with those seen proximal to the constriction. Although there were some similarities, the absence of granular vesicles, the decrease in the axonal endoplasmic reticulum and the ‘collapse’ of the axons due to the decrease in their contents were notable differences. It is suggested that there is a differential movement of axoplasm and organelles distal to the constriction. Thus while granular vesicles and some axoplasm continue to move towards the periphery, mitochondria and a part of the axoplasm migrate proximally to the site of axonal injury and the region of maximal degenerative change. The movement of mitochondria is considered to indicate a reaction to injury rather than supporting the view that retrograde axoplasmic flow occurs in normal axons.

An electron microscopic study of the early changes proximal to a constriction in sympathetic nerves

The ultrastructural changes, proximal to a constriction, in unmyelinated postganglionic sympathetic axons have been studied in the cat splenic and hypogastric nerves. They were con stricted with a fine ligature, which was left in situ , and examined at intervals up to 24h after operation. Immediately after tying the ligature there were definite changes in the morphology and organelle content of the axons adjacent to the constriction. These were due to the mechanical trauma produced by tying the ligature. From 10 min onwards there was a rapid accumulation of organelles in axons, which became progressively more swollen. Eventually the plasma membranes of both axons and Schwann cells broke down and later the Sclrwann cell basement membrane ruptured , allowing axonal organelles to escape into the interstitial spaces. The accumulating organelles included vesicles with an electron dense core, mitochondria, large vacuoles and myelin figures. Filamentous structures and both fine and wide tubules were more prominent and more numerous after operation. These were accompanied by a marked increase in the number of agranular vesicles. Tubular structures, morphologically similar to both the agranular vesicles and the vacuoles, were also very numerous. This similarity in appearance and the fact that many of these agranular vesicles, vacuoles and tubules were found joined together by either filaments or fine tubules suggests that they are part of the same system . At all times the greatest accumulation of organelles and the most marked axonal swelling was found in the first 0.5 to 1 mm segment of nerve immediately adjacent to the constriction. Less marked changes, affecting principally the agranular vesicles and finer tubules to gether with focal accumulations of mitochondria were seen at more proximal levels from 4h onwards. It is suggested that the axonal swelling is due to the accumulation of axoplasm and organelles. Two possible interpretations are discussed: (1) that this represents the effects of obstructing the normal flow of axoplasm from the cell body to the periphery, and (2) that some features, in particular the increase in the size and number of the various tubules may be indicative of an active reaction to the effects of axonal injury. These two phenomena probably take place simultaneously and are accompanied by degenerative changes.

Modulating effect of prostaglandin E2 on noradrenaline release from the isolated cat spleen.

Stimulation of the splenic sympathetic nerves in the dog and the cat has been shown to increase the outflow of prostaglandin from the spleen (Davies, Horton and Withrington 1967, Gilmore, Vane and Wyllie 1968). Recently prostaglandin E1 was found occasionally to reduce the release of noradrenaline (NA) caused by stimulation of the splenic nerves in the cat (Hedqvist and Brundin 1969).

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

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.

An immunohistochemical study of the adrenal medulla of the ox

The adrenal medulla of ox was studied by an indirect immunofluorescent technique using anti-ox chromaffin granule serum. The serum had a weak cross reaction with ox brain stem and splenic nerve. There was a species cross reaction with sheep, pig and horse. Immunoelectrophoresis showed five components in the serum against ox adrenal lysates. The whole adrenal medulla of ox was found to fluoresce by the immunofluorescent technique but not the cortex. The adrenals of sheep, pig and horse behaved similarly using the anti-ox serum. A serum prepared against ox chromogranin-A, the most abundant soluble protein of the chromaffin granules, was also used for immunofluorescence. Again both the adrenaline and noradrenaline storing cells fluoresced, but not the cortex.

The responses of the spleen to nerve stimulation in relation to the frequency of splenic nerve discharge.

The response of the spleen is shown to be made up of at least three distinct components, 2 vascular and 1 capsular. Although the splenic capsular response is maximal at frequencies of nerve stimulation well below 10 impulses per second, the response of the splenic vascular bed is less than 70% maximum with stimulation at 10 impulses per second (imp. /s). In the decerebrate cat the splenic nerve fibres are normally active at between 0 and 5.6 imp. /s and in asphyxia or following vertebral occlusion this activity can rise as high as 10 imp. /s.

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.

TRANSPORT OF NORADRENALINE IN SYMPATHETIC NERVES AND THE EFFECT OF NERVE IMPULSES ON ITS CONTRIBUTION TO TRANSMITTER STORES

Abstract— —A study has been made of the contribution of noradrenaline transport along sympathetic nerves to their terminal stores of transmitter by ligating the splenic nerves of the cat, and measuring both the noradrenaline that accumulates above the constriction, and the noradrenaline content of the spleen. The biochemical estimations were supplemented by fluorescence histochemistry. The effect of abolishing efferent impulses in the splenic nerves was examined by cutting their preganglionic nerve supply.The proximo‐distal flow rate for noradrenaline was calculated as 1.4‐3.3 mm/hr assuming that all the noradrenaline that accumulates is derived from the cell bodies in the ganglion without net addition or loss in the axons. The process was not dependent on impulse traffic in the nerves, since decentralization did not significantly effect the accumulation. The amount of noradrenaline arrested by the constriction in 24 hr was only 1 per cent of the stores in the terminals of those nerves, and consequently no change was detected in the spleen's noradrenaline content as a result of constricting its nerve supply.In the presence of an intact reflex pathway to the spleen, the stress of the operative procedure produced a marked constriction of the spleen, and depletion of its noradrenaline content. These changes could be prevented either by section of the preganglionic splanchnic nerves, or by ligation of the splenic nerves, thereby blocking the conduction of efferent nerve impulses.The evidence favours a proximo‐distal flow of noradrenaline in sympathetic nerves, independent of nerve impulses, which makes, however, a negligible quantitative contribution to the terminal stores of transmitter.

Proximo-distal transport of [14C]noradrenaline and protein in sympathetic nerves.

Abstract— —Both [14C]noradrenaline and [14C]leucine were injected into the coeliac ganglia of cats in an attempt to label the noradrenaline and protein of the granular vesicles, so that their movement in the splenic nerves could be followed.When a constriction was placed on the nerves, labelled noradrenaline and protein accumulated just proximal to it, but there was no such accumulation below it, nor above a second, more distal constriction placed on the same nerve. This indicated that a neural transport mechanism, rather than uptake from the circulation, was responsible for the accumulation.Peaks of labelled noradrenaline and protein were observed to move down the axon at about 5 mm/hr. In addition a slow moving component of axonal protein, advancing at about 1 mm/day, was detected.The results demonstrate a rapid proximo‐distal movement of noradrenaline and protein which could represent the transport of granular synaptic vesicles from their site of manufacture in the cell body to their site of storage in the nerve terminals within the spleen.

Abnormal regulation of catecholamine synthesis in pheochromocytoma.

Abstract The biosynthesis of catecholamines in two pheochromocytomas was compared with that in normal human adrenal gland tissue as well as bovine splenic nerve tissue. Tyrosine hydroxylase activity from the pheochromocytoma was far less sensitive to inhibition by catechol compounds than was the same enzyme preparation from either normal human adrenal gland or bovine splenic nerve tissue. Lack of a normal control mechanism, i.e., inhibition by catecholamine of the rate-limiting step in their own biosynthesis, may account, at least in part, for the uncontrolled excessive production of catecholamines often observed in pheochromocytoma.

Cation and metabolic requirements for retention of metaraminol by rat uterine horns.

British Journal of Pharmacology and ChemotherapyVolume 33, Issue 2 p. 277-286 Free Access CATION AND METABOLIC REQUIREMENTS FOR RETENTION OF METARAMINOL BY RAT UTERINE HORNS D. M. PATON, D. M. PATON Department of Pharmacology, University of Alberta, Edmonton, Alberta, CanadaSearch for more papers by this author D. M. PATON, D. M. PATON Department of Pharmacology, University of Alberta, Edmonton, Alberta, CanadaSearch for more papers by this author First published: June 1968 https://doi.org/10.1111/j.1476-5381.1968.tb00989.xCitations: 16AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL REFERENCES Bernstein, L. & Weatherall, M. (1952). Statistics for Medical and Other Biological Students, p. 86. London: E. S. Livingstone. Berti, F. & Shore, P. A. (1967). A kinetic analysis of drugs that inhibit the adrenergic neuronal membrane amine pump. Biochem. Pharmac., 16, 2091– 2094. Boullin, D. J. (1967). The action of extracellular cations on the release of the sympathetic transmitter from peripheral nerves. J. Physiol., Lond., 189, 85– 99. Bray, G. A. (1960). A simple efficient liquid scintillator for counting aqueous solutions in a liquid scintillation counter. Analyt. Biochem., 1, 279– 285. Daniel, E. E., Carroll, P. M., Robinson, K. & Graham, J. (1967). Adenine nucleotides, metabolic inhibitors, and ion fluxes in smooth muscle. In Ureteral Reflex in Children, ed. J. F. Glenn, pp. 29– 56. Washington: Nat. Acad. Sci. and Nat. Res. Council. Dengler, H. J. (1965). Effect of drugs on monoamine uptake in isolated tissues. In Proc. 2nd Int. Pharmac. Meeting, Pharmacology of cholinergic and adrenergic transmission, ed. G. B. Koelle, W. W. Douglas & A. Carlsson, Vol. 3, pp. 261– 275. Oxford: Pergamon. Giachetti, A. & Shore, P. A. (1966). Studies in vitro of amine uptake mechanisms in heart. Biochem. Pharmac., 15, 607– 614. Gillis, C. N. & Paton, D. M. (1966). Cation dependence of the norepinephrine-uptake process in heart slices. Circulation, 34, Suppl. 3, 110. Gillis, C. N. & Paton, D. M. (1967). Cation dependence of sympathetic transmitter retention by slices of rat ventricle. Br. J. Pharmac. Chemother., 29, 309– 318. Green, R. D. & Miller, J. W. (1966a). Evidence for the active transport of epinephrine and norepinephrine by the uterus of the rat. J. Pharmac. exp. Ther., 152, 42– 50. Green, R. D. & Miller, J. W. (1966b). The effect of various substances on the efflux of labelled catecholamines from the uterus of the rat. J. Pharmac. exp. Ther., 152, 439– 444. Gutman, Y. & Weil-Malherbe, H. (1967). Subcellular distribution of norepinephrine in uteri of some species. Nature, Lond., 214, 108– 109. Hays, R. M., Singer, B. & Malamed, S. (1965). The effect of calcium withdrawal on the structure and function of the toad bladder. J. cell. Biol., 25, 195– 208. Iversen, L. L. (1967). The uptake and storage of noradrenaline in sympathetic nerves, pp. 108– 146. Cambridge: Cambridge Univ. Press. Iversen, L. L. & Kravitz, E. A. (1966). Sodium dependence of transmitter uptake at adrenergic nerve terminals. Mol. Pharmac., 2, 360– 362. Keen, P. (1967). Release of d-l H3 norepinephrine from heart slices. Fedn. Proc., 26, 570. Kirpekar, S. M. & Misu, Y. (1967). Release of noradrenaline by splenic nerve stimulation and its dependence on calcium. J. Physiol., Lond., 188, 219– 234. Lundborg, P. & Stitzel, R. (1967). Uptake of biogenic amines by two different mechanisms present in adrenergic granules. Br. J. Pharmac. Chemother., 29, 342– 349. Paton, D. M. (1967). Cation dependence of metaraminol retention by rat uterus. J. Pharm. Pharmac., 19, 73– 74. Paton, D. M. & Daniel, E. E. (1967). On the contractile response of the isolated rat uterus to prostaglandin E1. Can. J. Physiol. Pharmac., 45, 795– 804. Slater, E. C. (1963). Uncouplers and inhibitors of oxidative phosphorylation. In Metabolic Inhibitors ed. R. M. Hochster & J. H. Quastel, Vol. 2, pp. 503– 516. New York: Academic Press. Titus, E. & Dengler, H. J. (1966). The mechanism of uptake of norepinephrine. Pharmac. Rev., 18, 525– 536. Webb, J. L. (1966). Enzyme and metabolic inhibitors, Vol. 3, pp. 1– 284. New York: Academic Press. Wurtman, R. J., Axelrod, J. & Potter, L. T. (1964). The disposition of catecholamines in the rat uterus and the effect of drugs and hormones. J. Pharmac. exp. Ther., 144, 150– 155. Citing Literature Volume33, Issue2June 1968Pages 277-286 ReferencesRelatedInformation

Effect of directly and indirectly acting sympathomimetic amines on adrenergic transmitter granules.

AbstractThe actions of various sympathomimetic amines on release and reuptake of noradrenaline (NA)1 in splenic nerve granules during incubation in phosphate buffer have been studied.The effect on the basic release rate was studied in the absence of NA in the medium.The degree of reuptake was determined with the aid of dl‐3H‐NA.Tyramine (TA) 10‐7–10‐4 M causes a moderate direct releasing effect of NA from nerve granules which reaches a constant level within 10 min at 20d̀.In 10‐5–10‐3 M concentration TA inhibits the reuptake of NA in granules.After previous loading of granules with radioactive NA, addition of TA to the incubation medium releases NA with apporoximately the same specific activity as that in the total store.Tritiated TA is taken up in nerve granules to a small extent, approximately corresponding to the direct release of NA.The releasing action of TA is blocked by reserpine 10‐5 M.phenoxybenzamine 3 X 10‐4 M and desmethylimipramine 3 X 10‐4 M.Phenethylamine and amphetamine have a strong direct releasing effect and a moderate effect on reuptake of NA in granules.Ephedrine and mephentermine slightly retard NA release and inhibit NA reuptake at 3 X 10‐4 M.Dopamine competitively inhibits reuptake of NA in granules.The effects of amines on release and reuptake in granules differ markedly from those exerted on the overall uptake of NA in perfused organs.

Vascular responses of the spleen to nerve stimulation during normal and reduced blood flow.

1. The splenic artery flow, the splenic weight and the arterial blood pressure were recorded in cats anaesthetized with sodium pentobarbitone.2. Oscillations in splenic artery flow and splenic weight were observed. Following occlusion and release of the splenic artery, there was a brief increase in flow to above the pre-occlusion level and the oscillations in flow were greatly increased in amplitude. It is suggested that the brief increase is a consequence of the reduction of arterial pressure and that the oscillations are due to synchronization of rhythmic activity of smooth muscle within the spleen.3. Stimulation of the splenic nerves resulted in decreases in splenic artery flow and splenic weight. The size of the responses varied with the frequency of stimulation and maximum responses in both flow and weight were obtained at about 3 impulses/sec.4. After stimulation for 10 min, the splenic weight response was maintained while the flow response showed some recovery towards the control level.5. When the splenic artery flow was reduced to about half the control level for periods up to 2 hr, the flow and weight responses to stimulation of the splenic nerves remained unchanged; the significance of this after a haemorrhage is discussed.6. Intravenous administration of atropine or propranolol did not affect the responses to nerve stimulation. After phenoxybenzamine, nerve stimulation caused a smaller decrease in splenic weight, while the splenic artery flow increased to above the control level. This increase was unaffected by atropine but abolished by propranolol.

Axoplasmic transport of 14C-noradrenaline and protein in splenic nerves.

MOST of the noradrenaline in postganglionic sympathetic neurones is bound within amine granules concentrated in the axon terminals1. These structures, which contain protein, are involved in the synthesis, storage and release of noradrenaline2. When a constriction is placed on the nerve trunk, noradrenaline accumulates proximal to it. This has been ascribed to the arrested distal transport of the granules from their site of manufacture in the cell body3, a view which is supported by electron microscope evidence of a corresponding accumulation of granular vesicles4. Their flow rate in cat sympathetic nerves of 10 mm/h, however, derived from the rate of noradrenaline accumulation3, is about 200 times that obtained for protein movement in somatic nerves (1 to 5 mm/day)5. Because the calculation assumes that no noradrenaline is synthesized, lost to or taken up from the circulation in the movement of the storage granules down the axon and at the site of constriction, an alternative method, labelling both noradrenaline and protein with isotopes, was used on the cat splenic nerves.

Reuptake and net uptake of noradrenaline in adrenergic nerve granules with a note on the affinity for 1- and d-isomers.

AbstractThe net loss of noradrenaline (NA) from bovine splenic nerve granules observed after incubation for 60 min at 20d̀ C in phosphate buffer is reduced in the presence of NA in the incubation medium. The effect is observed from 10‐7M NA and gradually increases so that at 10‐4M NA in the medium the net loss is small. By continuous removal of the NA in the medium by addition of potassium ferricyanide, the net loss reaches a maximum value which may represent the basic release rate. The effect of NA in the medium is due to reuptake of NA as indicated by the incorporation of dI‐3H‐NA in the granules during incubation. Preliminary observations suggest that the reuptake is also ATP‐dependent. During successive depletion of labelled stores at 20d̀, the specific activity of NA is unalterec indicating a uniformly labelled pool. In partially NA depleted nerve granules the net uptake of NA from the medium is enhanced by ATP‐Mg2and dependent on the NA concentration in the medium. A method for estimating the relative affinity of the l‐ and d‐isomer for nerve granules is described. The mean value found for the affinity ratio l‐NA/d‐NA was 9.4 (range 4.2–15.7). It is suggested that the continuous turnover of NA in the nerve storage granules is of major significance for the physiological transmitter homeostasis.

The uptake of isoprenaline in nerve granules

Isolated bovine splenic nerve granules take up isoprenaline to the same extent as noradrenaline or adrenaline. The uptake is enhanced by addition of ATP to the incubation medium. The results indicate that the low uptake of isoprenaline in tissues depends on an uptake barrier in the axon membrane rather than in the storage granules. This appears also to be true for adrenaline which is less readily taken up by the tissue than noradrenaline. It is concluded that the granules are protected from certain catecholamines by a discriminating mechanism located in the axon membrane.

Localization of different steps in noradrenaline synthesis to different fractions of a bovine splenic nerve homogenate

Experiments were carried out to determine to what extent the synthesis of noradrenaline in bovine splenic nerve tissue can proceed in the high-speed sedimentable particulate fraction that contains the specific noradrenaline storage vesicles. Various fractions of a homogenate of this tissue were incubated in a potassium phosphate medium together with radioactively labeled precursors of noradrenaline. The first two steps in the synthesis, the ring hydroxylation of tyrosine and the decarboxylation of dopa, were shown not to require the presence of this particulate fraction. On the other hand, this fraction was an absolute prerequisite for the last step, the β-hydroxylation of dopamine. No significant formation of catechol compounds from tyrosine could be demonstrated on incubation with this particulate fraction after it had been washed and resuspended in potassium phosphate. Some dopa decarboxylase activity remained in the particulate fraction even after washing. The results support the view that in this tissue only one enzyme involved in noradrenaline synthesis, dopamine β-hydroxylase, is truly located in the above-mentioned particles, possibly inside the membrane of the noradrenaline-storing vesicles. Tyrosine hydroxylase and dopa decarboxylase appear to be located outside these particles. Dopa decarboxylase shows some association with the particulate fraction studied, and might be, to some extent, bound to the outer aspect of the same particles which contain the β-hydroxylase, or could just be accumulated in the perivesicular parts of the probably highly organized axoplasm.

Noradrenaline formation from dopamine in isolated subcellular particles from bovine splenic nerve

The process of β-hydroxylation of dopamine (DA) and the fate of the newly formed noradrenaline (NA) were studied in high-speed sedimentable particles from bovine splenic nerves, after resuspension in potassium phosphate. The NA formation was found to be a linear function of the DA concentration in the medium. However, only a fixed amount of the newly formed NA was retained in the particulate fraction; the remainder appeared in the supernatant. Addition of NA to the medium reduced NA formation from DA, but hardly affected binding of the newly formed NA, while severely depressing DA retention. On the other hand, DA was shown to have about the same affinity as NA for the amine uptake mechanism of the particles. Reserpine added to the medium inhibited the formation of NA from DA, as well as the binding of NA and of DA, to an extent dependent on the drug/DA concentration ratio. The inhibition of NA formation was much less pronounced than that of firm amine binding. Although the results suggest that the membranes of the particles are permeable to NA and to DA, they do not rule out a certain inhibitory effect of reserpine on amine passage across the membranes. Washing was found to release loosely bound amines or amine derivatives from the particles. Loose binding appeared to be blocked by reserpine. The results indicate that deamination proceeds in the high-speed sedimentable particles. Inhibition of monoamine oxidase did not affect the NA formation from DA.

Adrenolytic and sympatholytic properties of 2-halogenoalkylamines in the vas deferens of the guinea-pig.

Adrenolytic and sympatholytic properties of 2-halogenoalkylamines in the vas deferens of the guinea-pig.

The accumulation of noradrenaline in constricted sympathetic nerves as studied by fluorescence and electron microscopy.

The effects of constricting post-ganglionic sympathetic nerves have been studied in the cat splenic nerve and guinea-pig hypogastric nerve. The results obtained using a fluorescence method for the histochemical localization of noradrenaline have been compared with electron microscopic findings. A close correlation was found between the accumulation of fluorescent material, attributable to noradrenaline, and of vesicles with an electron dense core (granular vesicles) believed to contain noradrenaline, proximal to the constriction in these nerves. This accumulation of noradrenaline was visible by 1 h after operation and increased rapidly in amount during the succeeding hours. It apparently reached a maximum after approximately 2 days and was found in what appeared to be newly formed axons 3 to 4 days after operation. Reserpine reduces the fluorescence and the number of vesicles with electron dense cores which accumulate proximal to the constriction. It is suggested, (1) that the fluorescent material is due, at least in part, to the presence of the granular vesicles, and (2) that the constriction has blocked the normal proximo-distal movement of noradrenaline which is believed to occur in post-ganglionic sympathetic axons.