Sympathetic control on salivary secretion by the parotid gland in rabbit. II. Effects upon the gland submitted to a weak parasympathetic stimulation (author's transl)]

Superior cervical ganglion stimulation significantly increases both, flow and amylase activity of saliva. Stimulation provokes two markedly different periods of flow: during the first half, flow is very high and differs significantly from the flow of the second half which closely resembles the one previous to stimulation. Alpha-adrenergic blocking agents, when administered intravenously, abolish the hypersecretion induced by sympathetic stimulation; beta-adrenergic blocking agents do not. These facts strengthen the hypothesis that alpha-adrenoceptors are most important in fluid secretion. The infusion of epinephrine acts similarly on cervical ganglion stimulation, but it differs because of its more diffuse effects and deeper cardiovascular alterations. Isoproterenol, after a long latency period, slightly increases salivary flow, which seemingly indicates that beta-adrenoceptors are involved in the fluid secretory processes although in a lesser degree than alpha-adrenoceptors.     

Parasympathetic control of secretion of pancreatic juice in the rabbit (author's transl)]

The secretion of pancreatic juice in response to stimulation of the vagus nerves in the neck, and to injection of parasympathomimetic drugs, was studied in anesthetized rabbits. Vagal stimulation caused a marked increase of protein content in pancreatic juice, and also a small increase in flow of juice, highly variable from one amimal to another, preceded by a short period of inhibition. Atropine supressed vagal effect on protein concentration, but failed to abolish the flow response. Injection of parasympathomimetic drugs closely imitated the results of vagal stimulation, with the difference that secretory action was fully abolished by atropine. The possibility that effects the parasympathetic stimulation on the flow of juice were secondary to vasodilatation, was discussed. The obtained data were compared with those described for other mammalian species, and the conclusion was reached that rabbit behaves like carnivora rather than herbivora.     

The ultrastructure of epithelial and myoepithelial oncocytes in the human parotid gland (author's transl)]

Oncocytes are well known to occur in the tissue of many organs for over 30 years. Their origin and function are less well known. We observed different types of oncocytes in a human parotid gland with the electron microscope. Besides a hyperplasia of mitochondria they show more or less advanced signs of membrane degeneration of these organelles. On the basis of our findings we discuss oncocyte formation as a special form of cellular aging in an otherwise healthy gland.     

Posterior hypothalamus action on gastric secretion (author's transl)]

Three groups of cats with surgically created total gastric pouches were employed in this experiment. They were divided as follows: in one group the innervation of the pouch was left intact; in another group the symphathetic innervation of the pouch was removed; and in the third group the pouch was completely denervated. It was seen that an infusion of histamine induced gastric secretion in all three groups. And when the secretion became constant it proved to be less acidic and more abundant in the sympathectomized group and also in the group that had suffered complete denervation. It was observed now that stimulating the posterior hypothalamus of the innervated group produced, in all of the cats, a decrease in the amount of acid secreted per unit of time. Consequently, it was seen that a symphathectomy did not eliminate the gastric effects produced when the posterior hypothalamus was stimulated. Specifically, stimulation of the posterior hypothalamus produced an increase in the amount of secretion rather than a decrease. The increase produced in these animals can be shown not to be due to irradiation of the anterior hypothalamus as the same response is obtained when a symphathectomy is combined with a vagotomy. It is, therefore, believed that it may be concluded that the Posterior hypothalamus does not produce its effect exclusively through its nervous pathways. It is believed its effect may possibly be mediated by an unknown substance liberated upon stimulation which then reaches the stomach by way of its blood supply.     

Amylase secretion by rabbit parotid gland. Role of cyclic AMP and cyclic GMP.

Amylase secretion and changes in the levels of cyclic AMP and GMP were studied in rabbit parotid gland slices incubated in vitro with a variety of neurohumoral transmitters, their analogs and inhibitors. Cyclic GMP levels increased 8-fold 5 min after exposure to carbachol (10(-4) M), without a change in cyclic AMP levels; amylase output also rose. These effects were completely inhibited by muscarinic blockade with atropine, but were unaffected by alpha-adrenergic blockade with phenoxybenzamine. Epinephrine (4 - 10(-5) M) produced a rapid increase in the levels of both cyclic nucleotides and in amylase release. The increase in cyclic GMP level was inhibited by previous exposure of the slices to phenoxybenzamine, while the cyclic AMP rise was prevented by the beta-blocking agent, propranolol. Pure alpha-adrenergic stimulation with methoxamine (4 - 10(-4) M) produced modest elevations in cyclic GMP content and amylase output, effects blocked by pre-treatment of slices with either atropine or phenoxybenzamine. At a concentration of 4 - 10(-6) M, isoproterenol (a beta-agonist) failed to affect cyclic GMP levels, but promptly stimulated increases in cyclic AMP levels, and after a short lag, amylase secretion. At a higher dose (4 - 10(-5) M) isoproterenol produced elevations in the levels of both nucleotides. The carbachol-induced effects on cyclic GMP content and amylase release were greatly potentiated by the addition of isoproterenol (4 - 10(-6) M). These data strongly suggest that cholinergic muscarinic agonists and alpha-adrenergic agonists stimulate amylase output in rabit parotid gland by mechanisms involving cyclic GMP. The atropine-sensitive intracellular events effected by alpha-stimulation may be dependent upon endogenous generation of acetylcholine. Both cyclic nucleotides seem to be required for the early rapid secretion of amylase. The unique responses achieved by the combination of carbachol and isoproterenol suggest that isoproterenol may increase the sensitivity of this tissue to the effects of cholinergic stimuli.     

Genetic counselling. I. Definition and present status (author's transl)]

Genetic counselling is a medical action which must be carried out by a M.D. specialized in genetics. Genetic counselling is peculiar in that couples rather than individuals are involved. Furthermore it is not concerned with the health of the consultants but with that of their expected children. Genetic counselling is not restricted to the statistical estimation of a risk; it raises important problems of psychology and behaviour. Finally, eugenic considerations about the diffusion of deleterious genes should not be taken into account in genetic counselling, which is given in the interest of individuals, not of the society. The increasing demand for genetic counselling is due to the change of the reproductive pattern. People do not want only to fix the size of their family, but also to avoid any accident of procreation.     

Restitution of granule stores in the rabbit parotid gland after isoprenaline-induced secretion

Summary A detailed stereological analysis has been made of the organelle content of rabbit acinar cells during the restoration of granule stores following extensive degranulation with isoprenaline (IPR). Rabbits were sacrificed 2, 4, 8, 12 and 16 h after IPR administration and the volumes and proportions of intracellular organelles were compared with those of untreated glands.At 2 h only 5% of cell volume was occupied by secretion granules, but there was already evidence of nascent granule formation. The volume per cell of secretion granules increased in sigmoid fashion and by 16 h amounted to 350 m³/cell, 36% of cell volume, which are values similar to those of the control replete glands. IPR treatment caused some initial swelling of the cells, and there were transient increases in the volumes of several compartments. However, the volume of mitochondrial and lysosomal compartments had returned to control levels by 4 h and that of the nucleus by 8 h. The greatest increase was in the volume of the rough endoplasmic reticulum which had increased by nearly 70% by 2 h and remained enlarged throughout the period of restitution. However, neither the volume nor the proportion of the smooth membraned compartment varied throughout the period of analysis.The results are analysed in the light of the overall response of the cells to IPR and the interaction of the organelles during the synthetic phase of the secretory cycle. They are presented as a basis for ensuing studies of the granule populations and the membrane composition of the cells during the restoration of granule stores.     

Effect of sympathetic stimulation on salivary secretion in submandibular gland in the rabbit stimulated by pilocarpine

The sympathetic stimulation under slow pilocarpine-induced flow conditions brought about a decrease in this flow rate that could be due to vasoconstriction, since such an effect was not observed after the administration of phentolamine (4 mg/kg i.v.). Contrariwise the injection of a beta-adrenergic blocking agent (propranolol 2-2.5 mg/kg i.v.) produced a decrease of the salivary flow rate that was even greater than in the control animals. These results suggest that the secretory effect in this gland and species is predominantly beta-adrenergic. The stated results are related to the changes observed in the blood outflow from the gland.     

Strain-specific antigens detected on murine tumour cells by means of rabbit heteroantisera (author's transl)]

The rabbit heteroantisera anti-Meth A sarcoma (H-2d) (RAMA) and rabbit anti-RBL-5 leukemia (H-2b) (RAR-5) have been used to study the presence of normal strain antigens on the surface of different murine tumour cells. RAR-5 detected H-2-like structures on TLX9 (H-bb) lymphoma, however RAMA did not on LSTRA leukemia (H-2d) mastocytoma. Neither RAR-5 nor RAMA contained antibodies against non-H-2 and differentiation antigens.     

Amylase secretion by rabbit parotid gland role of cyclic AMP and cyclic GMP

Amylase secretion and changes in the levels of cyclic AMP and GMP were studied in rabbit parotid gland slices incubated in vitro with a variety of neurohumoral transmitters, their analogs and inhibitors. Cyclic GMP levels increased 8-fold 5 min after exposure to carbachol (10⁻⁴ M), without a change in cyclic AMP levels; amylase output also rose. These effects were completely inhibited by muscarinic blockade with atropine, but were unaffected by α-adrenergic blockade with phenoxybenzamine. Epinephrine (4 · 10⁻⁵ M) produced a rapid increase in the levels of both cyclic nucleotides and in amylase release. The increase in cyclic GMP level was inhibited by previous exposure of the slices to phenoxybenzamine, while the cyclic AMP rise was prevented by the β-blocking agent, propranolol. Pure α-adrenergic stimulation with methoxamine (4 · 10⁻⁴ M) produced modest elevations in cyclic GMP content and amylase output, effects blocked by pre-treatment of slices with either atropine or phenoxybenzamine. At a concentration of 4 · 10^{−6 M}, isoproterenol (a β-agonist) failed to affect cyclic GMP levels, but promptly stimulated increases in cyclic AMP levels, and after a short lag, amylase secretion. At a higher dose (4 · 10⁻⁵ M) isoproterenol produced elevations in the levels of both nucleotides. The carbachol-induced effects on cylcic GMP content and amylase release were greatly potentiated by the addition of isoproterenol (4 · 10⁻⁶ M).These data strongly suggest that cholinergic muscarinic agonists and α-adrenergic agonist stimulate amylase output in rabbit parotid gland by mechanisms involving cyclic GMP. The atropine-sensitive intracellular events effected by α-stimulation may be dependent upon endogenous generation of acetylcholine. Both cyclic nucleotides seem to be required for the early rapid secretion of amylase. The unique responses achieved by the combination of carbachol and isoproterenol suggest that isoproterenol may increase the sensitivity of this issue to the effects of cholinergic stimuli.     

Uncharted cholinergic nerves in the rabbit parotid gland.

Cholinergic nerves are shown to be left in the rabbit parotid gland after avulsion of the auriculo-temporal nerve: a cholinesterase inhibitor injected through the duct caused secretion, thereby revealing leakage of acetylcholine from cholinergic nerve endings, and acetylcholinesterase positive nerves were found histochemically. The incomplete cholinergic denervation offers an explanation to the fact that some choline acetyltransferase activity remains in the 'denervated' glands.