The enzymic potential of tissue kallikrein (rK1) in rat submandibular saliva depends on whether it was secreted via constitutive or regulated pathways

The enzymic activity and immunoreactivity of rat tissue kallikrein (rK1) secreted at rest by granular duct cells of unstimulated submandibular glands has been compared with that secreted on autonomic nerve stimulation. Although a direct vesicular, constitutive secretory pathway operates for rK1 secretion from granular duct cells of unstimulated and parasympathetically stimulated glands the rK1 was not present in a pro-form and actually showed a greater enzymic activity per unit immunoreactive protein than the granule-derived rK1 in sympathetically evoked saliva. Constitutively secreted rK1 was found to be in a single chain molecular form by reducing SDS gel electrophoresis. In contrast rK1 secreted from the storage granule pool of granular duct cells on sympathetic nerve stimulation was present in much higher amounts and occurred in both one-chain and two-chain forms as revealed by SDS gel electrophoresis under reducing conditions. The lower enzymic potential of rK1 in sympathetically evoked saliva might be accounted for by its conversion to a two-chain form.     

Effects of secretory nerve stimulation on acid phosphatase and peroxidase in submandibular saliva and acini in cats

The effects of parasympathetic or sympathetic nerve stimulation either alone, or in combination, on the acid phosphatase-containing central acinar cells and the peroxidase-containing demilunar cells of the cat submandibular salivary gland have been investigated by histochemical and cytochemical techniques. The results obtained with these techniques were correlated with biochemical assays for both enzymes in the saliva secreted. The results indicate that, although both sets of nerves probably affect both sets of cells, the predominant secretory effect of parasympathetic stimulation is on the central cells and, conversely, the predominant secretory effect of sympathetic stimulation is on the demilunes. Sympathetic stimulation appeared also to have initiated synthesis of peroxidase in the demilunar cells, especially when it was superimposed upon parasympathetic stimulation.     

Submandibular secretion of immunoglobulins IgA and IgG in peripheral paralysis of the facial nerve

INTRODUCTION: In all lesions of the facial nerve suprachoroidally localized, and due to disturbance of parasympathetic and sympathetic component, there comes to qualitative and quantitative disorders of the secretion of submandibular salivary gland. Glandular immunoglobulins IgA and IgG are the secretion of the specific plasma cells in the interstice of this gland. The mechanism of the secretion of immunoglobulins is not sufficiently clear, but it is certainly under the direct neurogenic control, since the disorders of the secretion emerge after the denervation of the submandibular salivary gland. The aim of the study was to prove the direct relation between the degree of submandibular immunoglobulin secretion IgA and IgG, and the degree of the lesion of the facial nerve U which is vitally important in the clinical estimation of the peripheral paralysis of this nerve. MATERIAL AND METHODS: In 35 patients with peripheral idiopathic facial nerve paralysis, the quantity of the secreted immunoglobulins IgA and IgG was examined by laser nephelometar BLN, Module 3. The quantity of the secreted immunoglobulins IgA and IgG (mg lit) in the saliva of the paralysed side was indirectly compared to the secreted immunoglobulins of the healthy, i.e. control side. The examination was performed three times: a) after the appearance of the disease, in the first 30 days; b) two to three months later; c) after six to twelve months. RESULTS: The quantity of the secreted immunoglobulins is significantly higher in the saliva samples taken from the paralysed side (9.50U204.77 mg lit), in comparison with the samples taken from the healthy side (9.50U70.36 mg lit). In the group of patients with favourable results and significantly higher secretion (p 0.01) normalization occurred in the final period of observation. In patients with unfavourable results the difference in secretion was continuously present (p 0.05) (table 1). DISCUSSION: In the lesions of the facial nerve suprachoroidally localized, there comes to disorder concerning the secretion of immunoglobulins IgA and IgG by submandibular salivary gland, which can be applied in the estimation of the degree of paralysis and the prognosis of the final result. CONCLUSION: The results of the research show that in the peripheral idiopathic facial nerve paralysis, there comes to increased secretion of immunoglobulins IgA and IgG in submandibular gland, at the paralysed side. In the patients who, during the paralysis, show quicker fall and normalization of the previously increased quantities of immunoglobulins, the recovery of the motor function of the facial nerve comes more successfully and more certainly. The degree of the secretion of immunoglobulins IgA and IgG can be used for the estimation of the severely of the pathological process in the suprachoroidal part of the nerve, and it can be used as a reliable parameter for the prognosis of the paralysis outcome.     

Devices for saliva collection from the major salivary glands. Results in normal subjects

BACKGROUND: Collection of saliva produced by the major salivary glands may be accomplished either by cannulation of the glandular ducts or by the application of specific collecting devices to the emergence area of the glandular ducts. Those procedures are complex, slow, invasive and require skilled personnel. AIM: To report the design and application of a device to collect parotid saliva (snail collector) and another device to collect saliva from the submandibular/sublingual complex. MATERIAL AND METHODS: The saliva collection devices were tested in 40 healthy volunteers (20 male) aged 18 to 22 years old. Saliva was collected using conventional conditions, during 5 to 15 min. RESULTS: An average of 1 to 1.5 ml of saliva was collected in the 10-15 min period from both parotid and submandibular/sublingual glands. Flow rates from parotid glands were 80 microliters/min and 180 microliters/min from submandibular/sublingual glands. Parotid saliva had a protein and organic material concentration twice as high than saliva from submandibular/sublingual glands. The presence of human alpha-amylase duplet (Mr 55 kD and 58 kD) predominated in parotid saliva, whereas saliva from submandibular/sublingual glands had other molecular markers such as the lysozyme duplet (Mr 18.5 kD and 17 kD). CONCLUSIONS: The tested devices were easily applicable, comfortable and allowed the collection of both parotid saliva and submandibular/sublingual saliva from various subjects at once, under the supervision of a single professional.     

Effect of variation in dietary NaCl intake on total and fractional renal blood flow in the normal and mercury-intoxicated rat

The influence of parasympathetic and sympathetic nerves on the parotid gland of the rat was investigated. It was found that both divisions of the autonomic nerves evoke secretion and probably also motor effects in this gland. Secretion elicited on sympathetic stimulation was mediated both via alpha- and beta-adrenoceptors, while motor effects were mediated via alpha-adrenoceptors. On stimulation of the autonomic nerves a lower duct pressure was reached in the parotid than in the submaxillary gland, and on sympathetic nerve stimulation the flow of saliva always started later from the parotid than the submaxillary gland. These findings are discussed in the view of the different arrangement of the myoepithelial cells in the 2 glands.     

Effects of gentamicin on rat submandibulary gland functions

1. Submandibular saliva was collected from anesthetized gentamicin-treated and control rats using carbachol, isoproterenol and pilocarpine as secretagogue. 2. Intraperitoneal injection of a large single dose (80 mg/kg) of gentamicin caused marked changes in saliva flow rate, protein and electrolyte concentrations in the presence of parasympathetic or sympathetic agents used as stimulants. 3. The secretion of N-acetyl-beta-D-glucosaminidase in saliva was determined and there was a marked increase in the enzyme activity of saliva of gentamicin-treated rats in comparison to that of controls. 4. The results of this study suggest that gentamicin as an aminoglycoside antibiotic at the dose employed, can influence the secretory mechanisms of rat submandibular glands.     

Breast cancer diagnosis using N2 laser excited autofluorescence spectroscopy

Carbonic anhydrase VI (CA VI) is a secreted enzyme produced predominantly by serous acinar cells of submandibular and parotid glands. We have investigated the developmental pattern of CA VI production by these glands in the sheep, from fetal life to adulthood, using immunohistochemistry. Also, a specific radioimmunoassay for CA VI was used to measure changes in enzyme expression in the parotid gland postnatally. CA VI is detectable by immunohistochemistry in parotid excretory ducts from 106 days gestation (term is 145 days), in striated ducts from 138 days and in acinar cells from 1 day postnatal. The duct cell content of CA VI declined as the acinar cell population increased, a feature also of CA VI immunoreactivity in the submandibular gland. Production of CA VI by submandibular duct cells was detectable initially at 125 days gestation, and acinar production was not seen before 29 days post-natal. Apart from the differing ontogeny of CA VI production in ducts and acini of parotid and submandibular glands, there was a parallel pattern of CA VI expression during the development of these major salivary glands. With the development of the acinar tissues in the postnatal lamb, there was a dramatic increase (about 600-fold) in the level of expression of CA VI in the parotid gland between days 7 and 59 as measured by radioimmunoassay.     

Nervous regulation of the tone of the retractor penis muscle in the goat

The nervous control of the retractor penis muscle (rp) was investigated in the anaesthetized goat. Also, isolated field stimulated strips of the muscle were studied. The noradrenaline (NA) and acetylcholine (ACh) content of the rp was determined, and histochemistry for adrenergic and acetylcholinesterase (AChE) positive nerves was performed. The muscle exhibited spontaneous activity that persisted after section of all nerves. There was, however, also a tendency of the activity to follow the general vasomotor tone, which disappeared after section of the sympathetic chains. The excitatory adrenergic nerves which innervate the muscle come from the sympathetic chains and run along the pudendal, the hypogastric and the pelvic nerves. The rp has a dense network of adrenergic fibres and is very sensitive to excitatory adrenergic stimulation. It has a fairly large NA content, which is higher in old goats (5.95 +/- 0.42 micrograms g-1) than in young goats (2.87 +/- 0.78 micrograms g-1). Inhibitory non-adrenergic non-cholinergic (NANC) innervation reaches it via the pelvic and the hypogastric nerves. The maximum inhibitory response is reached at low frequencies (2-4 Hz). Cholinergic prejunctional inhibition of the excitatory response to sympathetic chain stimulation was effected by simultaneous stimulation of the hypogastric nerves. In vitro experiments confirmed the presence of endogenous cholinergic muscarinic suppression of the excitatory adrenergic neurotransmission. Significant amounts of ACh (0.81 +/- 0.18 micrograms g-1) are present in the muscle, and it contains strongly AChE positive nerve fibres and nerve cell bodies. It is concluded that the goat rp is innervated by sympathetic adrenergic excitatory nerves and parasympathetic NANC inhibitory nerves. It further has a direct sympathetic inhibitory NANC innervation, and an indirect inhibitory cholinergic innervation which at least in part is sympathetic.     

cDNA cloning and characterization of rat C5a anaphylatoxin receptor

lnterleukin-2 (IL-2) is known to cause xerostomia and skin manifestations similar to graft-versus-host disease (GVHD). We therefore evaluated major salivary gland function in patients with hematological malignancies treated with IL-2 and interferon-alpha (IFN-alpha) after ABSCT. Eleven patients (seven male, four female) of median age 40 (24-47) were evaluated, seven with non-Hodgkin lymphoma (NHL); one with Hodgkin's disease (HD) and three with acute myelogenous leukemia (AML). Parotid and submandibular salivary gland function was assessed before, during and after IL-2/IFN-alpha administration by evaluation of the salivary flow rate and the composition of secreted saliva. Significant reductions in both the resting and stimulated parotid and submandibular salivary flow rates were observed during IL-2/IFN-alpha immunotherapy compared with the pre- and post-therapy values (P < 0.01), while no hyposalivation was observed in the control patients who underwent ABSCT and did not received IL-2. Sialochemical evaluation revealed a significant increase in potassium concentration (24.4+/-0.6 mEq/l to 28.9+/-1.4 mEq/l) and a significant decrease in sodium concentration (6.7+/-2.1 mEq/l to 3.3+/-1.0 mEq/l) (P < 0.05) in the stimulated parotid gland saliva secreted during IL-2/IFN-alpha administration. Salivary protein concentrations were not altered by the IL-2/IFN-alpha immunotherapy. Similar changes were previously observed in mice and humans with chronic GVHD. We conclude that IL-2 immunotherapy induces major salivary gland dysfunction in humans, similar to our previous observations in patients with chronic GVHD, which may indicate similar pathophysiologic mechanisms.     

Abnormally high levels of cystatin S in submandibular glands, saliva, and gingiva of plaque-resistant rats

To identify salivary biomarkers of periodontal diseases, we used plaque-resistant and -susceptible rats as animal models. The levels of salivary cystatin S in saliva, salivary glands, and gingiva were tested in Nembutal-anesthetized young and adult plaque-resistant and -susceptible rats of both sexes with and without chronic treatment with isoproterenol. Isoproterenol was injected i.p. once a day for 4 or 6 consecutive days. Isoelectric focusing electrophoresis by the PhastSystem and the western blotting method were used to separate different proteins and to identify a salivary cystatin S band in these samples. The expression of salivary cystatin S mRNA was also determined by the northern blotting method. Depending upon the types of agonists, a few differences were observed in secretory functions between both strains of rats in both sexes, but the levels of salivary cystatin S in saliva elicited from the submandibular gland and in the extracts of the submandibular glands and gingiva were significantly higher in plaque-resistant rats when compared with those of plaque-susceptible rats in both sexes. However, no significant difference was seen between the strains after chronic treatment with isoproterenol. The N-terminal 26-amino-acid sequence of salivary cystatin S purified from submandibular saliva of plaque-resistant rats was identical with that purified from submandibular saliva of Sprague-Dawley rats subjected to chronic treatment with isoproterenol. The expression of salivary cystatin S mRNA was dramatic in the submandibular glands of the plaque-resistant rats and in the submandibular glands of Wistar rats subjected to chronic treatment with isoproterenol, but not in those of plaque-susceptible rats. These results suggest that salivary cystatin S might be a good biomarker in distinguishing between the two strains of rats and that its concentration is correlated with plaque resistance.     

Protein binding effects of salivary excretion of phenobarbital in dogs

The salivary excretion of phenobarbital was investigated by collecting parotid saliva (Pr) and mandibular-sublingual saliva (MS) separately after intravenous administration in beagle dogs. (1) The alterations in the proportions of saliva secreted by the different glands were produced by salivation stimulants such as citric acid, ascorbic acid, sodium chloride and sodium glutamate. (2) The phenobarbital concentrations in both Pr amd MS were lower than those in plasma. The drug concentrations in MS were significantly lower than in Pr with stimulus of 10% citric acid of 15% sodium chloride (p less than 0.05). There was a significant correlation between phenobarbital concentration in each saliva and plasma specimen ( p less than 0.05). (3) The stimulation with 10% citric acid produced higher saliva /plasma drug concentration ratios (S/P ratios: 0.923 +/- 0.175 for Pr, 0.633 +/- 0.073 for MS) than that with 15% sodium chloride (S/P ratios: 0.597 +/- 0.071 for Pr, 0.509 +/- 0.067 or MS). (4) The S/P ratios were hardly influenced by salivary flow rates, at least under the experimental conditions examined in this study. (5) The increased S/P ratios were observed with higher salivary pH and then the equation of Matin et al. 3) seemed to hold for the average values of salivary pH and S/P ratio. (6) The stimulation with 10% citric acid produced higher protein concentration in saliva and higher S/P ratio than that with 15% sodium chloride following alternate stimulations in the same dog.     

Selective processing of submandibular rat 1 protein at dibasic cleavage sites. Salivary and bloodstream secretion products

The amino acid sequence of submandibular rat 1 (SMR1) protein, deduced from its cDNA sequence, led to the prediction that the SMR1 gene encodes a hormone-like precursor [Rosinski-Chupin, I., Tronik, D. & Rougeon, F. (1988) Proc. Natl Acad. Sci. USA 85, 8553-8557]. SMR1 contains an N-terminal putative secretory signal sequence and a tetrapeptide (QHNP), located between dibasic amino acids which constitute the most common signal for prohormone processing. We have isolated and characterized from the male rat submandibular gland and its secretions three structurally related peptides, namely an undecapeptide (VRGPRRQHNPR), a hexapeptide (RQHNPR) and a pentapeptide (QHNPR) generated from SMR1 by selective proteolytic cleavages at pairs of arginine residues. The biosynthesis of these peptides is subjected to distinct regulatory pathways depending on the organ, sex and age of the rat. Furthermore, the peptides are differentially distributed in the submandibular gland and in resting or epinephrine-elicited submandibular salivary secretions, suggesting distinct proteolytic pathways for their maturation. The undecapeptide is generated in the gland of both male and female rats, but under basal conditions it is only released into the saliva in male animals. The hexapeptide is produced in large amounts in the gland of adult male rats and released into the saliva in both resting and stimulated conditions. The pentapeptide appears only in the male saliva and is present mostly under stimulated conditions. In addition, administration of epinephrine induces the release of the hexapeptide from the submandibular gland into the bloodstream. The evidence indicates that the rat submandibular gland can function as a dual exocrine and endocrine organ for the SMR1-derived hexapeptide, as has been reported for nerve growth factor, epidermal growth factor, renin and kallikrein. Although the biological activities of the SMR1-derived peptides are not yet known, their high production and adrenergic-induced release only into the saliva and bloodstream of adult male rats, suggest a physiological involvement in some male-specific processes.     

Regulation of salivary kallikrein secretion in submandibular gland

Unstimulated pairs of rat submandibular glands were compared with regard to their wet weight, total protein content and kallikrein antigenic activity. Paired glands from the same animal were found to be comparable, whereas differences from one animal to another were considerable. One of two paired glands was extirpated and used as control, and the other was subsequently subjected to stimulation. Salivary secretion was induced parasympathomimetically (intraperitoneal injections of pilocarpine; perfusion with acetylcholine and electrical stimulation of the ductal nerve plexus near the gland hilus) or sympathomimetically (cervical sympathetic nerve stimulation with or without administration of alpha- or beta-adrenergic blocker; perfusion with epinephrine, norepinephrine or isoproterenol). The effect was studied by measuring the change in total gland kallikrein content and by quantitation of kallikrein in saliva. A small secretion of kallikrein was always observed. However, alpha-adrenergic stimulation was 40 and 1 500 fold more effective in releasing kallikrein than beta-adrenergic and parasympathomimetic stimulation, respectively. Also, significantly more kallikrein was released by beta-adrenergic than parasympathomimetic stimulation. Immunohistochemistry confirmed the observed depletion of kallikrein following alpha-adrenergic stimulation. No alteration in kallikrein localization was observed in stimulated glands.     

Autonomic control of submandibular protein secretion in the anaesthetized calf

The autonomic control of submandibular secretion has been investigated in fully weaned, anaesthetized calves 7 weeks after birth. Stimulation of the parasympathetic (chorda-lingual) innervation invariably produced a flow of saliva, the rate of which was frequency dependent over the range 2-8 Hz continuously. Neither the rate of flow nor the output of protein was enhanced by stimulating in bursts at relatively high frequencies. Stimulation of the sympathetic innervation (20 Hz for 1 s at 10 s intervals) alone produced a much slower flow of saliva but with a considerably higher protein content. Stimulation of both together produced no greater flow of saliva than occurred with either alone at the lower frequencies (2 and 4 Hz) but there was a pronounced synergy in respect of the secretion of protein. Following pre-treatment with propranolol (1.0 mg kg-1 i.v.), during on-going chorda-lingual stimulation at 4 Hz, intra-arterial injections of 1 nmol of either vasoactive intestinal peptide (VIP) or pituitary adenylate cyclase activating peptide (PACAP) elicited an increase in the flow and protein output of about the same order of magnitude. Calcitonin gene-related peptide (CGRP) also produced these same effects with roughly half the efficacy of VIP and PACAP but substance P had no detectable effect. It is concluded that VIP, PACAP and possibly CGRP are candidates for neurotransmitters with a role in the control of secretion in this gland.     

Determination of salivary and serum immunoglobulin concentrations in the cat

The concentrations of immunoglobulin(Ig)G, IgM, and IgA were determined in unstimulated saliva (n=14), stimulated saliva (n=6), and serum (n=14) from healthy adult cats. Analysis by single radial immunodiffusion (SRID) was compared with class-specific enzyme linked immunoassays (ELISA), and good correlation was demonstrated between the two techniques. Mean (s.d.) serum concentrations of 19.08 (5.38) mg/ml IgG, 2.04 (0.83) mg/ml IgM and 2.6 (2.16) mg/ml IgA were obtained by SRID. The immunoglobulin concentrations of the saliva samples frequently fell below the quantification limits for SRID, however, all samples could be quantified by ELISA making this the method of choice for the determination of salivary immunoglobulin concentrations. IgA was the predominant class of immunoglobulin secreted by the major feline salivary glands, and the concentration of each immunoglobulin class was greater in unstimulated versus stimulated saliva. Analysis of sequential unstimulated saliva samples collected each morning and evening over a 4-day period from four cats revealed the salivary immunoglobulin concentrations to be relatively constant.     

Direct evidence of parasympathetic vasodilatation in cat periodontal ligament

Sympathetic regulation of periodontal ligament blood flow (PLBF) is well-attested; however, vasodilator responses mediated by parasympathetic nerve fibers have yet to be conclusively demonstrated in the periodontal ligament (PL). The present study was designed to determine whether parasympathetic vasodilator mechanisms do or do not exist in the cat PL. In our cats, the cervical sympathetic trunks were sectioned bilaterally prior to any stimulation in order to eliminate sympathetic effects on the vascular beds under study. Dynamic changes in PLBF, with mandibular lip blood flow (LBF) recorded for comparison, were investigated in cat mandibular canine teeth using laser Doppler flowmetry. The peripheral cut ends of the facial and glossopharyngeal nerve roots, which have been reported to contain parasympathetic nerve fibers to the oral tissues, were electrically stimulated intracranially. Such stimulation caused blood flow to increase in the ipsilateral PL and lip, without an increase in systemic blood pressure. These vasodilator responses in the PL and lip were sensitive to ganglion blockade (with hexamethonium), indicating vasodilation via activation of parasympathetic vasodilator fibers. In contrast, although intracranial stimulation of the trigeminal nerve root also induced increases in both PLBF and LBF, these were unaffected by hexamethonium, but reduced by tripelennamine, indicating antidromic vasodilatation via the trigeminal sensory nerve. These results suggest that parasympathetic vasodilator mechanisms do exist in feline PL.     

Submandibular salivary proteases: lack of a role in anti-HIV activity

Whole human saliva contains a number of proteolytic enzymes, mostly derived from white blood cells and bacteria in the oral cavity. However, less information is available regarding proteases produced by salivary glands and present in salivary secretions. In the present study, we have analyzed submandibular saliva, collected without contaminating cells, and identified multiple proteolytic activities. These have been characterized in terms of their susceptibility to a series of protease inhibitors. The submandibular saliva proteases were shown to be sensitive to both serine and acidic protease inhibitors. We also used protease inhibitors to determine if salivary proteolytic activity was involved in the inhibition of HIV infectivity seen when the virus is incubated with human saliva. This anti-HIV activity has been reported to occur in whole saliva and in ductal saliva obtained from both the parotid and submandibular glands, with highest levels of activity present in the latter fluid. Protease inhibitors, at concentrations sufficient to block salivary proteolytic activity in an in vitro infectivity assay, did not block the anti-HIV effects of saliva, suggesting that the salivary proteases are not responsible for the inhibition of HIV-1 infectivity.     

Low and high frequency electroacupuncture at Hoku elicits a distinct mechanism to activate sympathetic nervous system in anesthetized rats

To address the effect of electroacupuncture (Ea) on autonomic nerve activity, the responses of rhythmic micturition contraction (RMC), urine excretion (UE), blood pressure (BP), renal sympathetic nerve activity (RNA) and pelvic parasympathetic nerve activity (PNA) to Ea were investigated in urethane-anesthetized rats. The acupoint Hoku (Li-4) was tested with two different stimulation frequencies (2 Hz and 20 Hz). Elongation of the RMC cycle and an increase in UE associated with the elevation of BP and RNA was elicited during Ea at Hoku. However, the pressor response induced by low frequency Ea (LFEa) was different from that by high frequency Ea (HFEa), i.e. a tonic effect was elicited by LFEa, while a phasic one was induced by HFEa. These results imply that: (1) Ea at Hoku may selectively activate the sympathetic, but not the parasympathetic nervous system, (2) Ea at Hoku with a different stimulation frequency may elicit a distinct mechanism to activate the sympathetic nervous system and (3) Ea at Hoku may ameliorate the hyperactive bladder in clinical therapy.     

Irradiation-induced damage to the salivary glands: the role of redox-active iron and copper

The mechanism of irradiation-induced hypofunction of the salivary glands is a process that is not fully understood. Here we examine the hypothesis that intracellular and redox-active ions of iron and copper, which are associated with the secretion granules, play a catalytic role in the irradiation-induced damage. Rats were subjected to head and neck irradiation (15 Gy X rays) and allowed to recover for 2 months. The function of the parotid and submandibular glands was then determined by pilocarpine-stimulated salivary secretion. A 45% decrease in the function of both glands was obtained when compared to nonirradiated controls. Treatment prior to irradiation (90 min) with cyclocytidine (200 mg/kg) led to a massive degranulation of the parotid gland and yielded nearly complete protection from radiation-induced damage. In contrast, pilocarpine stimulation prior to irradiation led to a marginal degranulation of the parotid gland and yielded only 13% protection. Neither agent caused degranulation of the submandibular gland mucous cells or yielded functional protection of this gland. Treatment with both agents yielded a marked increase in iron, copper and manganese levels in the parotid gland saliva. An analogous marked increase in the redox activity of iron and copper ions was recorded for the parotid saliva stimulated by pilocarpine and cyclocytidine. Pilocarpine-stimulated submandibular gland saliva contained metal levels similar to those of the parotid gland saliva. However, no redox activity and no increase in metal mobilization could be demonstrated in the submandibular gland saliva stimulated by both agents. The correlation between the patterns of gland degranulation, mobilization of redoxactive metals and the protection of gland function, for both parotid and submandibular glands, focuses attention on the catalytic roles played by transition metal ions in promoting free radical reactions, which likely participate in the process of injury to the tissue.     

Functional properties of postganglionic sympathetic neurones supplying the submandibular gland in the anaesthetized rat

Sympathetic neurones supplying the submandibular salivary gland innervate blood vessels, secretory and myoepithelial cells. Here we examined whether these functionally different sympathetic neurones show distinct reflex response patterns. In anaesthetized rats, single unit activity was recorded from postganglionic axons projecting to the gland. Neurones were tested for their responses to stimulation of baroreceptors, cutaneous nociceptors and cold receptors and to gustatory stimuli applied to the tongue. Respiratory modulation was also analysed. Only a few postganglionic neurones identified electrically (5-10%) were spontaneously active. They were excited by noxious and cold stimuli, inhibited by baroreceptor stimulation and exhibited respiratory modulation. None of the units responded to gustatory stimuli. Thus, in anaesthetized rats spontaneously active sympathetic neurones supplying the submandibular gland behave like vasoconstrictor neurones. Sympathetic neurones with other functions are probably silent.