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At least 19 recordsLinked to original sources
PubMed1987

Differential effects of hypoxia on the turnover of norepinephrine and epinephrine in the heart, adrenal gland, submaxillary gland and stomach.

The authors examined the effects of hypoxia (8% O2 in N2) on the turnover rates of norepinephrine (NE) and epinephrine (E) in the heart, adrenal gland, submaxillary gland and stomach. The turnover rates were estimated by measuring the decrease in the content of NE and E after an i.p. injection of alpha-methyl-p-tyrosine (250 mg/kg), an inhibitor of tyrosine hydroxylase. After a 4-h exposure to hypoxia, the turnover rate of NE in the heart and those of NE and E in the adrenal gland were increased, whereas that of NE in the submaxillary gland was decreased. The turnover rate of NE in the stomach was unchanged. Pretreatment with hexamethonium, a ganglionic nicotinic receptor blocker, abolished the hypoxia-induced changes in the turnover rate of NE or E in the heart, adrenal gland and submaxillary gland. Furthermore, transection of the spinal cord at the level of C5-6 abolished hypoxia-induced alterations in the turnover rate of NE and E in the adrenal gland and submaxillary gland. In contrast, the hypoxia-induced changes seen in the heart persisted, although at a lower level, even after transection. These results show that the effects of hypoxia on the activities of the sympathoadrenal system differ depending on the organs; activities are increased in the heart and adrenal gland, decreased in the submaxillary gland and unchanged in the stomach. Furthermore, the present data suggest that hypoxia-induced alterations in the activities of cardiac sympathetic nerves originate in both the brain and spinal cord, including preganglionic neurons, whereas changes in the activities of the sympathetic nerves to the adrenal gland and submaxillary gland originate mainly in the brain.

Adrenal Glands↗
PubMed1991

Cell-specific expression of the glucocorticoid receptor within granular convoluted tubules of the rat submaxillary gland.

The submaxillary gland, a heterogeneous tissue composed essentially of two functionally distinct cell types (tubular epithelial and acinar), offers an interesting system in which to study the mechanisms of steroid-dependent growth and differentiation. One cell type, the granular convoluted tubular (GCT) cell, secretes a large number of physiologically important polypeptides, including epidermal and nerve growth factors. Two steroids, androgens and glucocorticoids, greatly influence the growth, differentiation, and secretory activity of GCT cells. Because glucocorticoids can partially mimic or potentiate androgen effects, it has been thought that glucocorticoids act via androgen receptors. Since the presence of glucocorticoid receptors is a prerequisite for glucocorticoid action, we have investigated the presence and cellular distribution of glucocorticoid receptors within the rat submaxillary gland. Binding experiments using [3H]dexamethasone revealed the presence of high affinity binding sites in rat submaxillary tissue homogenates. Most of these sites were specifically competed by dexamethasone, corticosterone, and a pure glucocorticoid agonist RU 28362. Neither testosterone nor dihydrotestosterone competed for glucocorticoid binding. The cellular distribution of glucocorticoid receptors within the submaxillary gland was investigated by immunocytochemistry, using two highly specific glucocorticoid receptor antibodies. The receptor was localized in the GCT cells, but not in the acinar cells of rat and mouse submaxillary tissue sections. In GCT cells, the glucocorticoid receptor colocalized with several secretory polypeptides, including epidermal growth factor, nerve growth factor, alpha 2u-globulin, and atrial natriuretic factor. These data suggest that the submaxillary gland is a target for glucocorticoid action and that at least part of the glucocorticoid effects on this tissue are mediated by bona fide glucocorticoid receptors.

Adrenalectomy↗
PubMed1975

A potent new mesodermal growth factor from mouse submaxillary gland. A quantitative, comparative study with previously described submaxillary gland growth factors.

A new growth factor with potent growth stimulating effects on connective tissue cells of the cornea has been isolated and partially purified from mouse submaxillary glands. A computerized image analysis system has been used to quantitate the growth responses of connective tissue fibroblasts to this new growth factor and to compare its activity with that of four previously described growth factors [nerve growth factor (NGF), epidermal growth factor (EGF), mesodermal growth factor (MGF), and thymocyte-transforming factor (TTF)] also obtained from mouse submaxillary glands. The new factor is as potent a growth stimulator as the previously described MGF. All five of the growth factors possessed esteropeptidase activity (trypsin-like) and general proteolytic activity. There was no correlation between the degree of growth stimulation of the connective tissue cells and either the esteropeptidase or general proteolytic activities of any of the growth factors.

Animals↗
PubMed1986

Prostaglandin-induced storage and secretion of esteroproteases in the mouse submaxillary gland.

The submaxillary glands of adult C3H mice which received intraperitoneal injections of prostaglandins F2 alpha and E2 (PGF2 alpha and PGE2) were examined biochemically and ultrastructurally. Results indicated that the specific activity of esteroprotease in an homogenate of submaxillary glands was significantly increased when mice were treated with PGF2 alpha (96 or 480 micrograms/kg), and decreased when they were treated with PGE2 (96 or 480 micrograms/kg). Ultrastructural findings were correlated with these biochemical data. Thus, it appeared that PGF2 alpha stimulated the secretion and synthesis of bioactive proteins, and that PGE2 stimulated only the secretion.

Animals↗
PubMed1986

The sequence of a cDNA clone coding for a novel kallikrein from mouse submaxillary gland.

Mouse submaxillary gland contains many proteolytic enzymes, the most widely studied of which are the kallikreins. This gland also contains high levels of nerve growth factor (NGF), which is isolated as a complex of three subunits, alpha, beta, and gamma. We report here the cloning and sequence analysis of a novel kallikrein from mouse submaxillary gland. Antibodies directed against the alpha subunit precipitate the product of this clone, but do not precipitate the homologous gamma subunit. This new kallikrein is therefore closely related to alpha NGF, yet in contrast to the alpha subunit, its sequence suggests it has proteolytic activity.

Amino Acid Sequence↗
PubMed1981

Histochemical demonstration of glucagon and serotonin by a fluorescent method in the rat submaxillary gland.

The submaxillary glands of young rats were examined in vivo and in vitro. Yellow fluorescence in some cells treated with o-phthalaldehyde was observed and they yielded a positive reaction on staining with phosphotungstic acid haematoxylin indicating the presence of glucagon. These cells were localized between secretory endpieces of the gland. In rats treated with L-5-hydroxytryptophan (L-5-HTP) cells similar in shape and size showed yellow fluorescence after the action of formaldehyde vapour. The results of histochemical studies and ultrastructural analysis seem to indicate the presence of cells similar to APUD endocrine cells in the rat submaxillary gland.

5-Hydroxytryptophan↗
PubMed1983

Turnover in vivo of alpha 1-adrenergic receptors in rat submaxillary glands.

In submaxillary glands, vas deferens, and cerebral cortex, [3H]prazosin labeled one homogeneous population of alpha 1-adrenergic receptors having a KD of 0.1 nM. Intravenous injections of phenoxybenzamine blocked these receptors in a dose-dependent manner without changing the affinity of the remaining sites for [3H]prazosin. The phenoxybenzamine efficiency was highest in submaxillary glands: 1 mg/kg completely blocked the alpha 1-adrenergic receptors but did not affect alpha 2-adrenergic, beta-adrenergic, and muscarinic receptors in this organ. After this blockade, the alpha-adrenergic receptors reappeared in the glands following a monoexponential time course. Analysis of this time course allows the determination of the rate constant for receptor degradation (k = 0.02 hr-1) and the rate of receptor production (r = 1.86 fmoles/mg of protein per hour). The half-life of the receptor was 33 hr. The reappearing receptors corresponded to newly synthetized receptors since their reappearance was blocked by i.p. injections of cycloheximide. Blockade of alpha 1-adrenergic receptors with phenoxybenzamine (2 mg/kg) did not affect receptor reappearance. In contrast, higher doses (4-20 mg/kg) decreased the velocity of receptor reappearance.

Animals↗
PubMed1987

Identification of the mucin core protein by cell-free translation of messenger RNA from bovine submaxillary glands.

Bovine submaxillary mucin was purified and subjected to chemical deglycosylation by treatment at 20 degrees C with either anhydrous hydrogen fluoride or trifluoromethane sulfonic acid. Virtually all of the sialic acid, galactose, fucose, and over 90% of the N-acetylhexosamines were removed by these treatments. The amino acid compositions of the deglycosylated and native mucins were similar indicating that chemical deglycosylation did not cause significant degradation of the protein. Antiserum specific for the deglycosylated bovine submaxillary mucin was produced by immunization of rabbits with the deglycosylated mucin. RNA was isolated from bovine submaxillary glands by extraction with guanidine hydrochloride and further fractionated by chromatography on oligo(dT)-cellulose to yield poly(A)+ mRNA. The poly(A)+ mRNA was translated in a rabbit reticulocyte cell-free translation system using [35S]methionine, [3H]leucine, [3H]threonine, [3H]proline, or [3H]serine as radiolabel and the translation products were analyzed by gel electrophoresis and fluorography before and after immunoprecipitation with the antiserum. A labeled product of molecular weight 60,000 was present in the immunoprecipitates obtained in the absence but not in the presence of the unlabeled competitor deglycosylated mucin. It is concluded that the primary translation product of the bovine submaxillary gland gene is a 60,000-dalton protein and that the monomer subunit of the mucin is about 170,000. Thus, in the native state the mucin consists of several self-associating subunits.

Amino Acids↗
PubMed1987

Alpha-adrenergic stimulation and radiosensitivity on the rat submaxillary gland.

The submaxillary glands were exposed to fractionated irradiation comparable to 50 Gy in clinical practice and a single fraction of 50 Gy. Half the number of rats were given cyclocytidine, an alpha-adrenergic agonist which depletes the serous cell granules before irradiation was embarked upon. Our results show that irradiation causes a significant, irreversible destruction of serous cells. With cyclocytidine pretreatment, the radiodamage was diminished and this drug is suggested to act as a radioprotector, depleting secretory heavy metal granules, and thus preventing radiodamage in the submaxillary salivary glands.

Ancitabine↗
PubMed1987

Structural properties of porcine submaxillary gland apomucin.

Porcine submaxillary gland mucin was deglycosylated with a mixture of pure glycosidases to give apomucin containing less than 1% carbohydrate. The resulting apomucin freed of glycosidases was found to contain nine amino acids: threonine, serine, glutamic acid, proline, glycine, alanine, valine, isoleucine, and arginine. Serine, threonine, glycine, and alanine comprise 77% of the composition. The molecular weight of apomucin was 96,500 as determined by gel filtration in guanidine hydrochloride. Its Stokes radius was greater than 68.6 A, a far larger value than expected for a globular protein with Mr = 96,500. Circular dichroism spectroscopy of apomucin suggests that it contains 42% aperiodic or "other" structure, 40% beta-turns, 10% antiparallel pleated sheet, and 8% helical structures. The predicted secondary structure of a 50-residue peptide from ovine submaxillary gland mucin resembles the circular dichroism predictions, being dominated by turns that would lead to an extended nonglobular structure. Analysis for the secondary structure of a 36-residue tryptic peptide derived from porcine submaxillary gland apomucin predicts a similar structure. It is concluded that apomucin is likely devoid of traditional secondary structure and serves as a scaffold upon which oligosaccharides are added in O-glycosidic linkage. When sufficient sialic acid is present in the oligosaccharides, native highly viscous mucin containing about two-thirds carbohydrate by weight is obtained.

Amino Acid Sequence↗
PubMed1976

Amino acid metabolizing enzymes in rat submaxillary gland, normal or neoplastic, and in pancreas.

The activities of 12 enzymes, many related to ornithine metabolism, were measured in rat submaxillary gland, submaxillary gland tumors and pancreas. In submaxillary gland, the activities of arginase, ornithine aminotransferase, pyrroline-5-carboxylate reductase and glutamine synthetase were high, but no ornithine transcarbamylase or proline oxidase could be detected. In the fetal submaxillary gland, arginase was at almost adult levels while ornithine aminotransferase reached 50% of its adult value postnatally. Submaxillary tumors deviated from their cognate tissue by lower levels of amino acid metabolizing enzymes and by high concentrations of thymidine kinase. In pancreas, none of the pyrroline-5-carboxylate metabolizing enzymes were as high as in either liver or submaxillary gland. The outstanding activities were those of gamma-glutamyl transpeptidase and glutamate dehydrogenase. Although arginase activities in submaxillary gland and pancreas were quantitatively similar, they differed qualitatively: submaxillary gland contained the same variant as liver while the pancreatic isozymes resembled those of other nonhepatic tissues.

Amino Acids↗