Expression of six mouse major urinary protein genes in the mammary, parotid, sublingual, submaxillary, and lachrymal glands and in the liver

Mouse major urinary proteins (MUPs) are encoded by a family of about 35 to 40 highly conserved genes. In the preceding paper (K. Shahan, M. Gilmartin, and E. Derman, Mol. Cell. Biol. 7:1938-1946, 1987), we presented the sequences of the most abundant MUP mRNAs in the liver (MUP I, II, and III) and in the lachrymal (MUP IV) and submaxillary (MUP V) glands. We have shown that these five mRNAs are coded by five distinct genes, MUP I through V. In the present communication, we examine the expression of MUP genes in all of the six tissues in which MUP mRNAs are synthesized, the mammary, parotid, sublingual, lachrymal, and submaxillary glands and the liver. We show that gene MUP II is expressed in the liver and in the mammary gland, that gene MUP IV is expressed in the lachrymal and parotid glands, and that gene MUP V is expressed in the submaxillary, sublingual, and lachrymal and parotid glands, and that gene MUP V is expressed in the submaxillary, sublingual, and lachrymal glands. Furthermore, we present evidence that in addition to genes MUP I through V, another gene, MUP VI, is expressed in BALB/c mice in the parotid gland. The tissue-specific synthesis of MUP mRNAs is thus brought about by two major mechanisms: the expression, in different tissues, of different members of the family and the expression of a single gene at various levels in different tissues. When a particular MUP gene is expressed in several tissues, transcripts of this gene initiate at the same site and are spliced and polyadenylated in the same manner.

Muscarinic receptors of rat parotid gland enlarged by gland ablation and bulk diet. Effects of denervation

The density of muscarinic binding sites was increased 10% in the rat parotid gland enlarged (2 times control) as a result of ablation of the submandibular-sublingual glands and maintenance of rats on bulk diet (50% inert cellulose plus 50% solid chow) for 4 weeks. When either the parasympathetic or sympathetic innervation to the gland was unilaterally removed at the time of submandibular-sublingual ablation and introduction of the bulk diet, the density of muscarinic receptors showed an even greater increase from levels of innervated glands of chow-fed controls (29%); with removal of both nerves, the increase was 39%. A 36% increase in cyclic guanosine monophosphate levels accompanied the increase in receptors of the enlarged gland, but when the parotid was denervated, there was no change in cyclic GMP. Absence of either or both nerves led to a maximal decrease of 24-29% in density of muscarinic receptors of parotid gland of chow-fed controls, but to no change in cyclic GMP levels. While autonomic influences mediate the changes in density of muscarinic receptors of parotid gland of chow-fed rats, some additional factor is apparently involved in their increase in the enlarged gland.

Beta-adrenergic and muscarinic receptors of parotid gland following maintenance of rats on liquid diet

Parotid gland of adult rats maintained exclusively on liquid (milk) diet for 7 or 13 days showed a 25% reduction in number of beta-adrenoceptors, and after 21 days, the reduction was 33%; with maintenance of rats on Metrecal for 7 days, the decrease was 24% for female rats and 22% for male rats. The decrease in number of muscarinic receptors after 7 or 13 days on milk was 32%, and 38% after 21 days; the decreases for rats on Metrecal for 7 days were 32% for females and 35% for males. In rats maintained on liquid (milk) diet for 7 days, and then denervated by unilateral removal of the parasympathetic and sympathetic innervations to parotid there were decreases of 39-42% in number of beta-receptors and 50-52% in muscarinic receptors at 6 or 14 days after denervation (maintenance on liquid diet for 13 and 21 days, respectively) from those of innervated glands of chow-fed rats; denervated glands of rats on chow diet showed the same reduction. Thus, it was concluded that absence of neurally mediated glandular activity, imposed by either diet or surgical removal of the nerves, caused marked decreases in number of both beta-adrenergic and muscarinic receptors, but that the presence of the nerves, even though inactive (liquid diet), provided a trophic influence that prevented the more marked decreases seen in the absence (surgical removal) of the nerves.

Electron microscopy of watery vacuole formation in rat parotid acinar cells during reflex stimulation

Reflex stimulation from eating hard chow caused variable degrees of watery vacuolation, most conspicuously in animals that had eaten the most food; this was accentuated by eating in the cold. Some vacuolation occurred in the absence of sympathetic impulses but there was much more in glands receiving both parasympathetic and sympathetic impulses. Vacuole formation was often associated with, but not dependent upon, a degree of acinar degranulation. The vacuoles appeared to originate either from the inner side of the Golgi apparatus, near condensing vacuoles, or from ballooning within the rough endoplasmic reticulum; some vacuoles appeared to arise close to secretory granules. Certain cellular components, including secretory granules, entered the contents of vacuoles, which also often had connections with lumina. Many basally-located vacuoles were large and bounded only by a tenuous layer of cytoplasm which was contained by the basal lamina. Vacuole formation may be related to strong stimulation of susceptible cells, which occurs to a variable extent during natural reflex secretion, as well as during artificial stimulation. Thus, under normal conditions, certain macromolecular components might enter saliva via this route and not solely by exocytosis. Leakages from acinar vacuoles could also occur into the glandular interstices, accounting for some of the parotid amylase found in peripheral blood.

Molecular cloning and chromosomal localization of human 4-beta-galactosyltransferase

A cDNA clone to human 4-beta-galactosyltransferase (EC 2.4.1.38) was isolated from a human liver lambda gt11 expression library by using a monospecific polyclonal antiserum to affinity-purified bovine enzyme. The authenticity of this cDNA clone has been demonstrated by several criteria. Under conditions of chronic treatment with the beta-adrenergic receptor agonist isoproterenol, rat parotid glands show an approximately 10-fold increase in 4-beta-galactosyltransferase activity. The increased enzyme activity was reflected in dot-blot analysis of control and isoproterenol-treated rat parotid RNA by using the human cDNA as probe. Hybrid-selection and in vitro translation identified a protein product with a molecular mass of 47 kDa that was immunoprecipitated with the bovine antiserum. The full-length human cDNA clone was then isolated and the DNA sequence for the NH2-terminal portion of the protein was deduced. Comparison of the NH2-terminal protein sequence from the bovine protein with that of the human cDNA clone confirmed its identity. In addition, the human cDNA clone was used to localize the gene for 4-beta-galactosyltransferase to human chromosome 4 by Southern analysis of a somatic cell hybrid panel.

Influence of superior cervical ganglion stimulation frequency on salivary secretion in the rabbit. Comparative study of parotid and mandibular glands

Saliva secretion in response to the stimulation of the superior cervical ganglion (S.C.G.) at different frequencies (2, 3, 5, 10, 15, 20 Hz) has been studied in anaesthetized rabbits. The differences between the two major glands in this species were analyzed, with respect to the flow response, potassium, amylase and total protein content during the sympathetic stimulation. The stimulation of S.C.G. increased the salivary flow rate at all frequencies, on both parotid and mandibular gland. In the parotid gland the flow and stimulation frequency show a positive linear correlation which does not appear in the mandibular gland. In conclusion, the differences observed in the response to sympathetic stimulation in both glands seem to be due to distinct patterns of sympathetic innervation on different glandular elements.

Isolation and sequence of a human gene encoding a potent inhibitor of leukocyte proteases

We report the isolation of the human gene encoding an inhibitor of neutrophil elastase and cathepsin G. We have sequenced the gene and a cDNA clone isolated from human parotid tissue. The protein encoded by this gene appears to contain two functional domains, one having a trypsin inhibitory site and the other an elastase inhibitory site. The two-domain structure of the protein is reflected in the organization of the gene, with each domain represented by a separate exon. We have also noted that the intervening sequence separating the trypsin-inhibitor-exon and the elastase-inhibitor-exon is flanked by eleven base-pair direct repeats, suggesting that this intron may have been generated by a transposition-type event.

Effect of duct ligation on amylase release from rat parotid slices

The effect of parotid duct ligation on amylase release from the rat parotid gland by isoproterenol was investigated in vitro. Unilateral ligation of the excretory duct progressively reduced amylase activity in the medium (the released amylase activity), but did not change the percentage of amylase release. Amylase activity in the parotid tissue decreased progressively after duct ligation, and the decrease rates of the amylase activity were very similar to that of the released amylase activity. Accordingly, the decrease of the released amylase activity after the ligation may be not due to an alteration in the amylase release mechanism, but due to the decrease of amylase content in the parotid tissue.

Effects of ouabain, amiloride, monensin, and other agents on ovine parotid secretion

Secretion by the parotid gland of Na-replete and -depleted sheep was investigated by examining the effects of modifiers of ionic transfer on salivary composition and flow rate. These agents were infused into the arterial blood supply of the vascularly isolated gland in anesthetized sheep. Ouabain inhibited Na+-K+ exchange in the ducts caused by Na depletion and restored the [Na+], [K+], and osmolality to close to those of Na-replete saliva. Ouabain also inhibited Cl- -HCO3- exchange in the ducts in Na repletion and depletion. Amiloride partially inhibited Na+-K+ exchange in Na depletion without affecting Cl- -HCO3- exchange. Monensin potentiated Na+-K+ exchange in Na repletion and depletion. Amiloride and monensin gained access to the saliva, but furosemide and ethacrynic acid were almost totally excluded, and, up to 10(-3) M in blood, they did not affect salivary composition or flow rate. Methazolamide gained free access to saliva but was without effect. 4-Acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid at 10(-3) M slightly increased salivary [Na+] and [HPO4(2-)]. The results indicate potent effects of ouabain on basolateral Na+-K+ pumps and of amiloride and monensin on transcellular delivery of Na+ to these pumps, but ouabain had no effect on salivary flow rate until O2 consumption approached zero and secretion failed. The findings do not support a proposal that the salivary secretion depends on a Cl- -dependent furosemide-sensitive system energized by Na+-K+-ATPase-dependent Na pumps.

Two types of cation channels in the basolateral cell membrane of human salivary gland acinar cells

Giga-seal patch-clamp single-channel current recording was applied to the basolateral cell membrane of human salivary gland acinar cells. The results indicate that the presence of Ca2+- and voltage-activated K+-channel having a unit conductance of 160 pS and Ca2+-activated Na+ permeable channel, having a unit conductance of 15 pS.

Immunochemical studies of an insulin-like material in the parotid gland of diabetic BB rats

Immunocytochemical and radioimmunoassay studies were performed on pancreatic and parotid tissues from diabetic BB and control Wistar rats. Compared with those of normoglycemic controls, the pancreata of diabetic BB rats generally lacked insulin-containing B-cells. Extracts from the parotid glands of diabetic rats contained less immunoassayable insulin-like material than was present in parotid extracts of controls. However, the parotid glands of both groups of animals contained numerous cells displaying insulin-like immunoreactivity. These insulin-immunoreactive cells, located mainly in the intercalated portion of the duct system, were comparable to those we reported recently in the parotid glands of normal and streptozocin-diabetic Sprague-Dawley rats. The presence of an insulin-like material in the parotid salivary gland of two types of diabetic animals suggests that such cells may be spared, in part, from the effects of both chemical and hereditary diabetogenic factors.

Spontaneous regeneration of the parotid salivary gland following juvenile recurrent parotitis

Sialograms of an 18-year-old female patient known to suffer from juvenile recurrent parotitis (JRP) disclosed the destructive glandular changes typical of the disease. During the 10 years subsequent to the sialographic examination, the patient did not experience any further attacks of JRP. Sialograms carried out when the patient was 28 years of age demonstrated a normal gland. This case illustrates that a damaged parotid gland is capable of regeneration following JRP.

Effect of pregestational sialoadenectomy of nursing mothers on eyelid opening of pups

The eyelid opening of pups born to and nursed by normal mice occurred by the 15th day of birth, whereas pregestational sialoadenectomy (removal of submandibular glands) of nursing mice delayed eyelid opening of their pups by as much as 5 days. Parotidectomy, however, had no effect on eyelid opening. Cross-foster nursing experiments indicated that the cause for delayed eyelid opening of pups was to be found in sialoadenectomized mothers, not their pups. Sialoadenectomized mothers had underdeveloped mammary glands that produced approximately 50% less milk than controls, and the amount of epidermal growth factor in their milk was similarly reduced. When epidermal growth factor, a polypeptide produced by the submandibular gland, was injected daily at a dose of 5 micrograms into sialoadenectomized pregnant mice, the eyelid opening of the pups nursed by their mothers occurred normally. These results are discussed with regard to the possible role of the submandibular gland and epidermal growth factor in neonatal eyelid opening.

Activation of Ca2+-dependent Cl- and K+ conductances in rat and mouse parotid acinar cells

Isolated acinar cells from rat and mouse parotid glands were studied with patch-clamp whole-cell current recordings. Acetylcholine (ACh) stimulation caused a transient inward current at a membrane potential of -70 mV, and a sustained outward current at a membrane potential of 0 mV, in quasi physiological Na+, K+ ion gradients, except the zero-Cl- ion gradient condition across the membrane. The reversal potential obtained from the ACh-evoked steady current was about -75 mV, in this ionic condition. When major Cl- ions of both the pipette and the bath solution were replaced, either by glutamate or by sulphate, only a large outward current was observed, at a membrane potential of -60 mV, in the presence of ACh. The addition of Ca2+-ionophore A23187 caused responses similar to those evoked by ACh. The reversal potential of A23187-induced current was close to the K+ equilibrium potential of -90 mV, in a Cl- -free condition. When K+-free NaCl solution was used in the pipette and the bath, A23187 caused only a large inward current, at a membrane potential of -60 mV. The reversal potential of A23187-evoked current was about -15 mV, in a symmetrical K+-free, NaCl condition. These results suggest that the ACh and A23187 activate Cl- as well as K+ conducting pathways via an increase in [Ca2+]i in the parotid acinar cells. The A23187-evoked large K+ current could not be explained solely by a rise in open probability of the channels.

Correlations between human salivary levels of lysozyme, lactoferrin, salivary peroxidase and secretory immunoglobulin A with different stimulatory states and over time

Within-subject correlations for the levels of these salivary proteins were determined in unstimulated and stimulated parotid saliva collected from 8 subjects and for stimulated parotid saliva collected from the same subjects once a week for a 4-week period. Initial correlations between unstimulated and stimulated samples were high and statistically significant (p less than 0.05) for all four proteins. When data were adjusted for variation attributable to flow rate and total protein, some correlations remained the same and those for lysozyme, lactoferrin and salivary peroxidase increased. However, the correlation for secretory immunoglobulin A decreased to a point where it was no longer statistically significant. In the weekly comparison, within-subject correlations across weeks were significant (p less than or equal to 0.05) for lysozyme, lactoferrin and salivary peroxidase, but not for immunoglobulin A. After adjustment for flow rate and total protein, the pattern of correlation was unchanged. Thus the relative rankings of subjects for levels of lysozyme, lactoferrin or salivary peroxidase may be consistent across stimulatory states, even though absolute concentrations may change; levels of these proteins in stimulated parotid saliva may be maintained over time. Secretory immunoglobulin A appears to be more subject to short-term variation.

Beta-adrenergic receptor mechanisms in rat parotid glands: activation by nerve stimulation and 3-isobutyl-1-methylxanthine

The technique of electrical field stimulation (e.f.s.) was employed in conjunction with selective pharmacological antagonists to specifically investigate the role of endogenous neurotransmitter(s) in the activation of beta-adrenergic receptor mechanisms in isolated parotid gland segments of the rat. The field-stimulus-induced amylase release due to beta-adrenergic receptor activation was characterized as that persisting in the presence of atropine (10(-5) M) and phentolamine (10(-5) M) and susceptible to blockade by propranolol (5 X 10(-6) M), i.e. combined beta 1- and beta 2-receptor blockade. The selective beta 1-receptor antagonist metoprolol (10(-5) M) was as effective as propranolol in blocking the beta-mediated enzyme release. The selective beta 2-receptor antagonist, H35/25 (10(-5) M) did not significantly affect the field-stimulus-induced amylase release. In the absence of any phosphodiesterase inhibitor the levels of cyclic AMP in the tissues were close to the limit of detection. Field stimulation was however associated with a fourfold increase in cyclic AMP. By comparison isoprenaline (10(-5) M) gave rise to a tenfold increase in cyclic AMP. The changes in cyclic AMP metabolism, in response to both field stimulation and isoprenaline, were greatly enhanced in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). The field-stimulus-induced increase in cyclic AMP was abolished by the beta 1-adrenergic receptor antagonist, metoprolol, but persisted in the presence of the beta 2-adrenergic antagonist, H35/25. IBMX was found to have a potent direct effect on amylase release. IBMX (10(-3) M) also gave rise to a tenfold increase in cyclic AMP. IBMX is then as effective as 10(-5) M-isoprenaline in stimulating both enzyme secretion and cyclic AMP metabolism. The secretory response to IBMX was unaffected by beta-adrenergic blockade by propranolol, was independent of extracellular calcium and did not give rise to 86Rb+ efflux. Importantly, isoprenaline (10(-5) M) failed to evoke any significant increase in amylase release if introduced during sustained superfusion of IBMX, yet it is in such protocols that the greatest changes in cyclic AMP metabolism are seen. The study clearly demonstrates that the beta-adrenergic-receptor-regulated amylase release in response to nerve stimulation is mediated predominantly, if not exclusively, by the beta 1-receptor subtype.(ABSTRACT TRUNCATED AT 400 WORDS)

A comparison of the haemodynamic effects of dietary sodium restriction and acute sodium depletion in the conscious sheep

The use of a low Na, low K sorghum grain diet supplemented with intraruminal electrolyte infusions has enabled dietary manipulation of sodium status to be studied in the sheep. Dietary sodium restriction reduced urinary sodium excretion within 24 h with maximal retention after 3 days. There were no other substantial metabolic or haemodynamic changes. A more severe form of sodium deficiency produced by parotid salivary drainage resulted after only 2 days in a sodium deficit 3-4 times that seen with 14 days of sodium restriction. Extracellular fluid volume and cardiac output decreased. Blood pressure was unchanged but there was an increase in peripheral resistance and plasma renin concentration.

Electrolyte composition of parotid saliva from sodium-replete red kangaroos (Macropus rufus)

Saliva was collected from the parotid salivary gland of anaesthetized sodium-replete red kangaroos (Macropus rufus) by catheterization of the parotid duct through its opening in the mouth. Salivary secretion was stimulated by ipsilateral intracarotid infusion of acetylcholine at varying rates to produce salivary flow rates ranging from 0.056 +/− 0.0042 (S.E. of mean) to 4.509 +/− 0.1136 ml min-1. The concentrations of sodium (142.2 +/− 1.93 to 157.0 +/− 1.17 mmol l-1), calcium (40.1 +/− 7.08 to 72.8 +/− 8.0 mumol l-1) and bicarbonate (68.6 +/− 3.48 to 143.3 +/− 0.67 mmol l-1) and the osmolality (270.1 +/− 2.98 to 291.7 +/− 2.10 mosmol kg-1) were positively correlated with salivary flow rate, whereas the concentrations of potassium (11.4 +/− 0.57 to 6.92 +/− 0.19 mmol l-1), magnesium (206.0 +/− 34.1 to 9.3 +/− 0.78 mumol l-1), hydrogen ion (17.0 +/− 1.89 to 6.82 +/− 0.49 nmol l-1), chloride (30.7 +/− 2.41 to 4.11 +/− 0.23 mmol l-1) and phosphate (47.6 +/− 2.65 to 14.9 +/− 0.81 mmol l-1) were negatively correlated with flow rate. The relationships between flow rate and concentration were curvilinear for all the inorganic solutes. The rates of secretion for each ion and for total solute were positively correlated with salivary flow rate. These regressions for sodium, potassium, calcium, hydrogen ion, bicarbonate and osmolality were always linear, with highly significant correlation coefficients and variance ratios, which indicated that the changes in concentration of these ions were related solely to flow rate and were not due to any other factor modifying glandular function. Spontaneous secretion was not observed during anaesthesia.

An individualized plastic intraoral device for the collection of human parotid saliva

A new individualized, non-invasive device for the collection of parotid saliva is described which offers the following advantages: automatic placement in the proper position for saliva collection by patients without the help of a technician, lack of deadspace, lack of salivary leakage around the device, elimination of cross contamination between patients, and unlimited re-use. Because of its simplicity, it is an ideal device for routine collection of parotid saliva samples in therapeutic drug monitoring, biochemical monitoring of exposure to toxic materials, and detection of secretory component deficiencies of immune system disorders.

Effect of denervation on parotid gland function

In 110 subjects with traumatic severance of secretory nerves, salivation was studied to determine the effect of denervation on gland function. A sequence of responses was found in which an initial hyperpositive response to cholinergic agents was blocked by atropine (stage I); this effect was reversed and increased salivation occurred in both latent (stage II) and overt (stage III) forms of the atropine paradox. The hypothesis suggested is that chemoreceptive cells of parotid membranes include a minimum of five populations of cholinergic receptors which respond differentially to parasympathetic agonists and antagonists.