Biomedical subjects
Publications and source records attributed to D Templeton.
Using fluorescent histochemical methods it has been shown that the villi of the jejunum are innervated by noradrenergic fibres. Varicose fibres originating in the plexus associated with the arterioles of the submucosa run close to the central lacteal and extend to the villus tip. It is suggested that the nerves may be involved in the control of absorption although exactly which structure in the villi are innervated remains unclear.
Horseradish peroxidase was applied to a ligation of the chorda tympani nerves running alongside the submandibular duct in order to label the preganglionic parasympathetic salivatory neurons in the brain stem. Labelled neurons were found in the ipsilateral motor trigeminal nucleus, lateral reticular formation and in the facial motor nuclei of both sides. However, the labelling of neurons in the motor nuclei of the trigeminal and facial nucleus was caused by the uptake of horseradish peroxidase by axons in the musculature surrounding the injection site which were probably damaged by the dissection procedure. The salivatory neurons were fusiform multipolar cells which were mainly located in the ipsilateral nucleus reticularis parvocellularis. No evidence for salivatory neurons in the nucleus supragenualis was found.
Using a continuous amylase assay the effect of a simultaneous stimulation of adrenergic and cholinergic receptors on amylase release by perfused rat parotid slices was investigated. Superimposing adrenergic stimulation (isoprenaline) on continual submaximal cholinergic stimulation (acetyl-beta-methylcholine) resulted in an augmented amylase release compared with the sum of the two separate effects. This could also be shown with continual adrenergic stimulation with cholinergic stimulation superimposed on this. Possible explanations of this effect are discussed with particular respect to the role of Ca++.
A method of continuous automated amylase assay is described. This relies on the absorption of iodine by starch to produce a blue color that can be quantified colorimetrically. Digestion of the starch by amylase released from parotid tissue slices reduces the intensity of the color formed, allowing quantification of the amylase released. The assay in sensitive to 0.05 U/amylase/ml and linear up to 13 U/ml. Typical tissue responses to acetyl-beta-methylcholine and isoprenaline are presented.
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The spinal origin of the sympathetic vasoconstrictor and secretory fibres to the submaxillary gland of the rat was identified in the pithed rat preparation by means of selective stimulation of small segments of the spinal outflow. Secretory and vascular responses were similar following stimulation in pithed rats to those following stimulation of the isolated superior cervical nerve trunk in anaesthetized rats. The spinal origin of the secretory and vascular fibres was coincident and it is concluded that if a separate control of blood flow and secretion by sympathetic fibres does exist that it must occur at the level of C.N.S. but that the nerves share a common pathway to the gland.
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The influence of the autonomic nerves on sublingual glands of rats was studied. Stimulation of the chorda-lingual nerve evoked a lively flow of saliva and was also thought to contract the myoepithelial cells in the gland. Sympathetic nerve stimulation, on the other hand, usually evoked no secretion and did not cause any motor responses in the sublingual gland. The glandular blood flow was increased by chorda-lingual nerve stimulation, and this vasodilatation persisted also when atropine had been administered. Sympathetic nerve stimulation decreased the sublingual blood flow; this vasoconstrictor effect was mediated via activation of alpha-adrenoceptors.
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The sensitivity to methacholine of the parotid glands in rats maintained on a liquid diet (aiming at sensitization) for a period of 2 weeks or 3-4 weeks was compared with that of the parotid glands in rats on a pelleted bulk diet (aiming at desensitization). In the rats on the liquid diet, it was found that the dose needed to evoke a just perceptible secretion of saliva was smaller, that the secretion started earlier and continued over a longer time period, and further that the amount of saliva secreted expressed per gland weight in response to submaximal doses of the sialogogue drug was bigger when compared with the rats on the pelleted bulk diet. These findings are interpreted as signs of a higher degree of sensitivity of the glands in the rats on the liquid diet than of those in the rats on the pelleted bulk diet.
Electrical stimulation of either the parasympathetic or the sympathetic nerve supply to the parotid and submaxillary glands increases the intracellular level of cyclic GMP and the rate of DNA synthesis and cell division while only sympathetic stimulation raises cyclic AMP levels. The periods of electrical stimulation inducing hyperplasia also raise the cyclic GMP concentration but there is no similar correlation with changes in cyclic AMP levels. However, the extent of hyperplasia induced by parasympathetic and sympathetic stimulation is not directly related to the size of the increase in cyclic GMP concentration that these treatments produce. Changes in cyclic AMP levels are reflected in altered in vitro adenylate cyclase activity. This activity is raised after 2 min sympathetic stimulation and markedly decreased with 30 min sympathetic or parasympathetic stimulation. Guanylate cyclase activity shows no such changes with nerve stimulation.
1. The cyclic AMP content of the rat salivary glands was measured after sympathetic and parasympathetic nerve stimulation, and after the administration of isoprenaline and phenylephrine. 2. Stimulation of the sympathetic nerves (20 Hz, 1 msec supramaximal voltage for 30 sec of every min) initially raised the cyclic AMP level in both the parotid and submaxillary glands. The rise, which was blocked by propranolol, was not maintained and declined during stimulation from the maximum (reached after 3 min stimulation) to control levels after approximately 15 min. Stimulation of the parasympathetic nerves for 5 min did not raise the cyclic AMP levels. 3. Isoprenaline and phenylephrine raised the cyclic AMP level in both glands. 4. Theophylline enhanced the growth of the parotid and submaxillary glands as measured either by an increase in the wet and dry weights or in acinar axes lengths. N6O2-dibutyryl cyclic monophosphoric acid (dibutyryl cyclic AMP), did not enhance the growth of the glands. 5. It is concluded that cyclic AMP does not directly control cell growth in the rat salivary glands but may be a 'trigger' for events leading eventually to increased growth.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.