Cytochemical localization of ouabain-sensitive, K+ -dependent p-nitrophenylphosphatase and Ca++-stimulated adenosine triphosphatase activities in human parotid and submandibular glands

Subcellular localization of epidermal growth factor receptor in human submandibular gland

The subcellular distribution of the epidermal growth factor receptor (EGFr) was demonstrated in the normal human submandibular gland by means of immunogold cytochemistry. EGFr labelling appeared in both acinar and ductal cells, where strong immunoreactivity was associated with a tubulovesicular system near the basolateral surfaces. In addition, groups of reactive vesicles were highlighted among secretory granules of both serous and mucous cells and at the apex of ductal cells. Basolateral vesicles were interpreted as being a result of EGFr internalization after activation by an exogenous ligand, although the functional meaning of those located apically remains unclear.

Primary culture of polarized human salivary epithelial cells for use in developing an artificial salivary gland

Therapeutic irradiation for head and neck cancer, and the autoimmune disease Sjogren's syndrome, lead to loss of salivary parenchyma. They are the two main causes of irreversible salivary gland hypofunction. Such patients cannot produce adequate levels of saliva, leading to considerable morbidity. We are working to develop an artificial salivary gland for such patients. A major problem in this endeavor has been the difficulty in obtaining a suitable autologous cellular component. This article describes a method of culturing and expanding primary salivary cells obtained from human submandibular glands (huSMGs) that is serum free and yields cells that are epithelial in nature. These include morphological (light and transmission electron microscopy [TEM]), protein expression (immunologically positive for ZO-1, claudin-1, and E-cadherin), and functional evidence. Under confocal microscopy, huSMG cells show polarization and appropriately localize tight junction proteins. TEM micrographs show an absence of dense core granules, but confirm the presence of tight and intermediate junctions and desmosomes between the cells. Functional assays showed that huSMG cells have high transepithelial electrical resistance and low rates of paracellular fluid movement. Additionally, huSMG cells show a normal karyotype without any morphological or numerical abnormalities, and most closely resemble striated and excretory duct cells in appearance. We conclude that this culture method for obtaining autologous human salivary cells should be useful in developing an artificial salivary gland.

Mineralocorticoid receptors in the mammalian olfactory mucosa

Mineralocorticoid hormones regulate secretion and absorption in a wide variety of epithelial tissues, although specific mechanisms in the olfactory mucosa are currently unknown. Utilizing reverse transcription-polymerase chain reaction (RT-PCR) analysis, we have demonstrated the expression of mineralocorticoid (type I) receptor messenger RNA in the rodent olfactory mucosa. Amplification products of predicted size were obtained with nucleotide sequences corresponding to respective mineralocorticoid receptor (MR) kidney transcripts. Immunocytochemistry, using an antibody with known specificity for MRs, was then utilized in order to localize the cellular site(s) of MR protein expression in the olfactory mucosa. The highest levels of MR immunoreactivity were localized to the supranuclear region of sustentacular cells, as well as the acinar cells of the Bowman's glands. The respiratory regions of the nasal cavity were devoid of appreciable MR immunoreactivity. This study demonstrates both MR transcript and protein expression in the olfactory mucosa. We hypothesize that the mineralocorticoid hormones may have a role in modulation of olfactory secretion and/or sensory transduction in the peripheral olfactory system.

Localization of zinc in the rat submandibular gland and the effect of its deficiency on salivary secretion

To clarify the role of zinc in the mechanism of salivary secretion, the effects of zinc deficiency on the morphologic findings and secretory function of the salivary gland were investigated with a rat model of chronic zinc deficiency, prepared by feeding a zinc-deficient diet, and a rat model of acute zinc deficiency, prepared by administration of a zinc chelator, dithizone. In rats with chronic zinc deficiency, the granule production in the granular duct cells was decreased, but the glandular epithelial cells and myoepithelial cells showed no degenerative or other destructive morphologic changes. The degranulation of the granular duct cells and acinar cells in response to acetylcholine hydrochloride seen in control rats was strongly inhibited in rats with acute and chronic zinc deficiency. The contractile response of the actin microfilament bundles in the myoepithelial cells to acetylcholine seen in the control rats was also absent in the zinc-deficient rats. Further, electron microscopy of the submandibular gland stained by Timm's method disclosed prominent zinc localization at the membrane surface, granules, and vesicles of the glandular epithelial cells and in the pits of the myoepithelial cells. These findings suggest that zinc, together with many zinc-dependent enzymes, is closely involved in the production and degranulation of secretory granules in the glandular epithelial cells, and also in the contraction of the myoepithelial cells in the submandibular gland.

Chronic submandibular sialadenitis: ultrastructure and phosphatase histochemistry

Eleven specimens of chronic submandibular sialadenitis were examined. A reduction in secretory material in acinar cells was seen with increasing atrophy until the acini resembled intercalary ducts. Myoepithelial cells and basement membrane were sometimes more conspicuous. Striated ducts showed a reduction of the folding of the plasma membranes in the basal part, and striated and excretory ducts showed a reduction in mitochondria. This possibly represents a functional atrophy secondary to reduced salivary flow. Very atrophic parenchyma largely consisted of simple cells. Phagosomes and apoptotic bodies were occasionally seen, and appear to be involved in the atrophy. Thiamine pyrophosphatase in the Golgi apparatus and acid phosphatase in the GERL were demonstrated in moderately atrophic parenchyma. This is similar to normal and indicates continuing synthetic activity. Acid phosphatase was demonstrated in lysosomes, which appear to be involved in the atrophy by their role in phagy. Alkaline phosphatase was occasionally demonstrated at luminal surfaces, and is likely to be involved in resorption of obstructed luminal contents. The changes are similar to those seen in experimentally obstructed glands and indicate that much of the parenchyma survives by adaptation to the altered environment which forms the basis for the successful results following conservative therapy.

Intercellular material in the basal and lateral folds of parotid serous cells in four species of bats

BACKGROUND

Basal folds are slender plications at the basal surface of acinar cells in the salivary glands of many mammalian species. These largely organelle-free folds increase the surface area of the basal plasmalemma manyfold and are unquestionably involved in the translocation of organic and inorganic molecules and water into the acinar cells.

METHODS

Specimens of salivary glands were obtained from over 230 species of live-trapped bats from major areas of the globe. Tissues for electron microscopy were fixed and processed by conventional means.

RESULTS

A number of the bat species examined had dense material in the intercellular spaces between basal and lateral folds of serous cells in the parotid gland. This intercellular material was particularly prominent in three species of New World bats, viz., Pteronotus parnellii, P quadridens, and Phyllostomus latifolius, and in one species of Old World bats, Chalinolobus argentatus. This dense material, which has a farinaceous texture, appears not to pass through tight junctions, so it is excluded from the lumina of intercellular canaliculi and acini. The dense material originates in the acinar cells--it is carried to the membranes of the folds via coated vesicles, which empty their dense content by exocytosis into the intercellular space. Similar dense material is present in the intercellular spaces of the basal labyrinth of striated ducts in the two species of Pteronotus. The manner in which this material accumulates in the striated duct is unclear.

CONCLUSIONS

Although the function of the intracellular dense material is undetermined, it appears to be placed strategically to influence molecular traffic into acinar cells or to modulate the paracellular pathway. From a comparative evolutionary perspective, we hypothesize that, in bats, the combination of basal folds and extracellular densities is associated with insectivory. Similar morphologies appear to be lacking in frugivorous or nectarivorous species.

3D-structure of cells of human salivary glands as seen by SEM

To demonstrate by SEM the topography and cytoarchitecture of the different parenchymal components of human salivary glands, we have employed a number of techniques that allow either the exposure of internal and lateral cell surfaces or, following the removal of connective tissue, the visualization of endpieces, ducts, and myoepithelial cells. Serous glands consist of indented acini attached to the ducts in a grape-like fashion, whereas mucous and mixed glands are made up of smooth tubuli. Myoepithelial cells (mecs), which are abundant on the surfaces of acini, tubuli, and intercalated ducts, are sparse on striated ducts. They are star-shaped on acini, striated ducts, and most of the tubuli. Spindle-shaped mecs are seen, instead, on intercalated ducts and, occasionally, on mucous and mixed tubuli as well. Cells of striated ducts split into a number of large basal portions whose surface is covered by long laminated processes responsible for the striations seen with TEM. Excretory ducts are lined by small cup-shaped basal cells and by tall cylindrical cells, which are completely covered by short processes oriented at random. When observed from below, after removal of the basal lamina, the basal surfaces of cells of excretory ducts exhibit polygonal areas delimited by short reliefs. Those of striated ducts show, instead, long laminar processes arranged radially. Results presented here are discussed and put in relationship to the mechanism of saliva production.

Aldosterone mediates an increase in [3H]ouabain binding at Na+, K(+)-ATPase sites in the mammalian inner ear

Na+,K(+)-ATPase has been implicated in the maintenance of high [K+], low [Na+] in endolymph of the inner ear, ionic properties considered to support transduction by the receptor cells. In exocrine ion-transporting epithelia, Na+,K(+)-ATPase activity is modulated by aldosterone, a mineralocorticoid hormone. In the present study, the effect of alteration of serum aldosterone levels on Na+,K(+)-ATPase in ion-transporting regions of the mammalian inner ear was investigated. A high Na+/low K+ diet offered ad libitum for 5 days was utilized to significantly decrease serum aldosterone in male Hartley guinea pigs compared to controls. An injection of aldosterone (10 micrograms/100 g b.wt.) 21 h prior to sacrifice resulted in significant elevation of serum aldosterone over that obtained with the high Na+/low K+ diet. Binding of [3H]ouabain, a specific inhibitor of Na+,K(+)-ATPase, was significantly elevated in microdissected lateral wall of the basal turn of the cochlea and in the ampulla of the semicircular canal, for aldosterone-injected vs. vehicle-injected animals. Serum [Na+] and [Cl-] were elevated in animals on the high Na+/low K+ diet and unaltered by administration of exogenous aldosterone. The enhancement of ouabain binding in inner ear tissues observed in aldosterone-injected animals, therefore, did not appear to reflect an alteration of serum electrolytes per se. The results of these experiments are consistent with the hypothesis that aldosterone increases the number of Na+,K(+)-ATPase sites in ion-transporting epithelia of the mammalian cochlea and semicircular canal.

A Ca(2+)-ATPase from rat parotid gland plasma membranes has the characteristics of an ecto-ATPase

A Ca(2+)-ATPase with an apparent Km for free Ca2+ = 0.23 microM and Vmax = 44 nmol Pi/mg/min was detected in a rat parotid plasma membrane-enriched fraction. This Ca(2+)-ATPase could be stimulated without added Mg2+. However, the enzyme may require submicromolar concentrations of Mg2+ for its activation in the presence of Ca2+. On the other hand, Mg2+ could substitute for Ca2+. The lack of a requirement for added Mg2+ distinguished this Ca(2+)-ATPase from the Ca(2+)-transporter ATPase in the plasma membranes and the mitochondrial Ca(2+)-ATPase. The enzyme was not inhibited by several ATPase inhibitors and was not stimulated by calmodulin. An antibody which was raised against the rat liver plasma membrane ecto-ATPase, was able to deplete this Ca(2+)-ATPase activity from detergent solubilized rat parotid plasma membranes, in an antibody concentration-dependent manner. Immunoblotting analysis of the pellet with the ecto-ATPase antibody revealed the presence of a 100,000 molecular weight protein band, in agreement with the reported ecto-ATPase relative molecular mass. These data demonstrate the presence of a Ca(2+)-ATPase, with high affinity for Ca2+, in the rat parotid gland plasma membranes. It is distinct from the Ca(2+)-transporter, and immunologically indistinguishable from the plasma membrane ecto-ATPase.

Identification of osteoblast-specific monoclonal antibodies

A series of four antibodies against rat osteoblasts have been produced using the hybridoma technique. After bone cells isolated from newborn rat calvariae by a sequential digestion procedure were cultured for 3 days, the cells were trypsinized and further maintained in rotation cultures overnight. Out of the cultured bone cells alkaline phosphatase-positive cells were sorted by flow cytometry and used as immunogens. The clones secreting the antibodies were selected on the basis of the abilities of these antibodies to bind to the bone cells but not to fibroblasts from neonatal rat head skins, in an enzyme-linked immunosorbent assay. Clones of two hybridomas, designated AOB-1 and AOB-2, were used to characterize the antigenic determinant(s) in osteogenic cells. The antibody showed the reactivity with isolated alkaline phosphatase-positive cells, osteogenic tissue cells in newborn rat calvaria, and mandibula, but not with the cells in head skin, lung, kidney, liver, or stomach as determined by immunofluorescence study. Western blot analysis has identified the antigenic determinants possessing apparent molecular weights of 210,000, 110,000, 65,000, 58,000, 40,000, 36,000, 32,000, 28,000, 25,000, 17,000, and 15,000 of osteoblast-rich monolayer cultured cells. According to the cell surface detection with biotin-avidin protein blotting technique, these fractions appear to be present as components of the cell surface of the osteoblast.

Ultracytochemical study of capillary Ca2+-ATPase activity in brain edema

To investigate the functional relationship between astrocytes and Ca2+-ATPase of cerebral capillary endothelial cells (capillary Ca2+-ATPase), cold lesions were produced and the cytochemical reaction (CR) for Ca2+-ATPase activity and morphological changes of astrocytes were chronologically studied. Under normal conditions, CR for capillary Ca2+-ATPase activity was mild. However, at 20 min after the operation, astrocytic end-feet embracing the capillaries were swollen, and CR was moderate. Deposits of slightly coarsened reaction product (RP) appeared and accumulated on the abluminal surface. CR became stronger as edema fluid accumulated. At 4, 7 and 15 days, detachment of the astrocytic processes from the capillary wall was observed and in the uncovered capillaries, CR was intense, especially on the abluminal surface. It could be thus possible that the enzyme was related to the blood-brain barrier (BBB). At 2 months, reactive astrocytes had recovered lesion-resistant capillaries. CR was mild and its associated deposits were coarser, the number decreasing on both surfaces. The nature and localization of the deposits of RP in the scar were different from those under normal conditions, possibly due to the functional differences between normal and reactive astrocytes in the BBB. CR was mild in association with astrocytes embracing the capillary wall and was intense without astrocytes. Therefore, it might be possible that astrocytes exerted certain effects on capillary Ca2+-ATPase activity in relation to BBB function.

Ultrastructural phosphatase histochemistry of submandibular and parotid salivary glands of man

Thiamine pyrophosphatase was demonstrated in the Golgi complex and acid phosphatase in the GERL of acinar cells of submandibular and parotid glands and were previously demonstrated in cells of intercalary ducts. Thiamine pyrophosphatase was also demonstrated in the Golgi complex of cells of striated and excretory ducts and myoepithelial cells. Acid phosphatase was also demonstrated in lysosomes. Alkaline phosphatase was rarely demonstrated light microscopically at luminal surfaces of striated and excretory ducts and electron microscopically in luminal vesicles in cells of striated ducts. The demonstration of the phosphatases in Golgi complexes and GERLs indicates that investigations on these structures in experimental animals are relevant to human salivary glands and supports the opinion that ductal cells as well as acinar cells secrete organic material. The presence of alkaline phosphatase at luminal surfaces of striated and excretory ducts suggests that resorption as well as secretion may occur in them.

Localisation of calcium-activated adenosine-triphosphatase (Ca2+-ATPase) in intracerebral arterioles in acute hypertension

The plasma membrane calcium-activated adenosine triphosphatase (Ca2+-ATPase) is known to regulate intracellular calcium levels. This enzyme was localised in intracerebral cortical vessels of normotensive and acutely hypertensive rats. Of interest was whether the arterioles that develop increased permeability to horseradish peroxidase (HRP) in acute hypertension demonstrate any alteration in localisation of Ca2+-ATPase as compared to normotensive controls. Rats were injected with HRP intravenously and acute hypertension was induced by a 2-min infusion of angiotensin amide. Following perfusion of fixative, brains were sliced and reacted for demonstration of HRP reaction product and Ca2+-ATPase. Normotensive rats showed discontinuous distribution of Ca2+-ATPase on the outer plasma membranes of endothelial, smooth muscle and adventitial cells of arterioles. The localisation of Ca2+-ATPase in pinocytotic vesicles present in endothelial and smooth muscle cells was quite striking. Focal cortical areas of hypertensive rats showed increased arteriolar permeability to HRP. Permeable arterioles showed marked reduction of Ca2+-ATPase on the outer plasma membranes of endothelium and smooth muscle cells as compared to nonpermeable arterioles of the same animals and arterioles of normotensive controls. The latter finding suggests that calcium may be involved in increased cerebrovascular permeability mechanisms in acute hypertension.

Cytochemical localization of Ca++-ATPase activity in the lateral cochlear wall of the guinea pig

Ca++-ATPase activity was examined cytochemically in the lateral cochlear wall of the guinea pig. The reaction products showing Ca++-ATPase activity were found along the folded plasma membrane of the strial marginal cells. In contrast, little or no reaction was seen on the apical surfaces of these cells. There were also marked reaction products on the microvilli and the endolymphatic cell surface of Reissner's membrane, and the apical and lateral plasma membranes of the spiral prominence and the external sulcus cells. These reactions completely disappeared when Ca++ or ATP was removed from the incubation medium. Our results strongly suggest that Ca++-ATPase plays an important role in Ca++ transport system for the regulation of Ca++ concentration in the cochlear endolymph.

Neuroendocrine control of secretion in pancreatic and parotid gland acini and the role of Na+,K+-ATPase activity

The results of our investigations into the localization of Na+,K+-pump activity in pancreatic and parotid acinar cells and the effects of hormones and neurotransmitters on pump turnover can be integrated with data on other aspects of stimulus-response coupling to construct models of the neurohumoral control of protein, fluid, and electrolyte secretion (Fig. 23). In both tissues, Ca2+ and cyclic AMP serve as intracellular messengers. In pancreatic acinar cells, the Ca2+-dependent pathway activated by the occupation of CCK or cholinergic receptors provides the primary stimulus for digestive enzyme secretion. Cyclic AMP plays a comparatively minor role; VIP and secretin are much less effective stimulators of protein secretion. Conversely, cyclic AMP levels in parotid acinar cells, which are modulated primarily through occupation of beta-adrenergic receptors, are a major determinant of enzyme secretion. Activation of the Ca2+-dependent pathway by cholinergic or alpha-adrenergic agonists or substance P is less important. The presence of dual control processes in each gland suggests that the observed differences in effectiveness of cyclic AMP- versus Ca2+-dependent secretagogues may reflect not different mechanisms, but rather a shift in the relative emphasis placed on each pathway. This emphasis could conceivably result from subtle variations in the interaction between cellular protein kinases and phosphatases and their phosphoprotein substrates. Electrolyte secretion, on the other hand, appears to involve both discrete and common entities. In pancreatic acinar cells from rodent species, cholinergic or CCK receptor occupancy elicits a Ca2+-dependent increase in the open-state probability of nonselective cation channels in the basolateral plasma membrane. The resultant influx of Na+ and efflux of K+ is most probably the factor which activates Na+, K+-pumps. Based on electron probe studies of the effects of cholinergic agonists on acinar cell Na+ and K+ contents discussed earlier, a transient reduction in the intracellular K+/Na+ ratio of up to 4-fold may occur. A shift of this magnitude in the cytoplasmic microenvironment of the Na+, K+-pump clearly would have a stimulatory influence (see discussion by Jorgensen, 1980). In addition, Ca2+ itself may have direct effects on Na+,K+-pump activity. Calcium at levels much above 1 microM progressively inhibits Na+,K+-ATPase activity (Tobin et al., 1973; Yingst and Polasek, 1985). In unstimulated guinea pig pancreatic acinar cells, Ca2+i measured by quin-2 fluorescence was 161 +/- 13 nM (Hootman et al., 1985a) which increased to a maximal concentration of 803 +/- 122 nM following CCh stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Histochemical studies of Ca-ATPase, succinate and NAD+-dependent isocitrate dehydrogenases in the shell gland of laying Japanese quails: with special reference to calcium-transporting cells

In order to elucidate the problem of which cells are involved in calcium transport and to estimate the role of mitochondria in calcium transport in the avian shell gland, the fine structure and the Ca-ATPase, succinate dehydrogenase (SDH) and nicotinamide adenine dinucleotide (NAD+)-dependent isocitrate dehydrogenase (NAD+-ICDH) activity of the shell gland of egg-laying Japanese quails were examined. The surface epithelial cells, consisting of ciliated cells with cilia and microvilli and non-ciliated cells with microvilli, had many large and electron-dense granules. The tubular-gland cells occupied the proprial layer and lacked secretory granules. When an egg was in the shell gland, the well-developed mitochondria of tubular-gland cells characteristically tended to accumulate in the apical cytoplasm, while they were scattered throughout the cytoplasm when an egg was not in the shell gland. Intense Ca-ATPase activity was found on the microvilli of tubular-gland cells, and moderate activity was found on the lateral-cell surface. In the surface epithelial cells, the basolateral cell surface showed moderate enzymatic activity. Both SDH and NAD+-ICDH activity were found in tubular-gland cells when an egg was in the shell gland. These results strongly suggest that calcium for eggshell calcification is actively transported by the tubular-gland (depending on Ca-ATPase activity) and that the mitochondria of gland cells may play an important role in this process as an energy source.