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PubMed1979

The renal handling of amylase in normal man.

The renal glomerular and tubular transport rate of amylase was studied by measuring the urinary excretion of this protein before and during inhibition of tubular protein reabsorption by lysine. The excretion of amylase was compared with the excretion of albumin, beta-2 microglobulin and free light chains of immunoglobulins. This investigation showed that amylase is reabsorbed by the tubular cells, but only to a very modest degree compared with the reabsorption of the other three proteins. In the case of amylase only about 45% of the filtered molecules are reabsorbed, whereas more than 90% of the filtered amount of the other molecules is reabsorbed by the tubular cells. The excretion of amylase rose after lysine injection only by a factor 1.8, whereas excretion rose by a factor 28 for albumin, 1,500 for beta-2 microglobulin, 16 for kappa chains and 8 for lambda chains. Minimal values for tubular reabsorption were found to be 5.5 +/- (SD) 4.3 U/min for amylase, 174.0 +/- 35.7 micrograms/min for albumin, 90.5 +/- 14.4 micrograms/min for beta-2-microglobulin, 70.4 +/- 17.4 micrograms/min for kappa chains and 24.2 +/- 9.2 micrograms/min for lambda chains.

Adult↗
PubMed1988

Adrenergic effects on secretion of amylase from the rat salivary glands.

The present study was undertaken to investigate the effect of adrenergic agents on secretion of amylase from the salivary glands in vivo. Saliva was collected from the distal oesophagus in conscious rats. Adrenaline increased the concentration of amylase in saliva and serum significantly. The result of infusion of alpha- and beta-adrenergic antagonists as well as noradrenaline and isoproterenol showed that secretion of salivary amylase is predominantly mediated by stimulation of beta-adrenergic receptors, especially of the beta 1-subtype. Investigation of the isoenzyme pattern in saliva, pancreatic juice and serum demonstrated that the major component in serum is salivary amylase. This study has shown that beta-adrenergic agents stimulate secretion of amylase from the salivary glands in rats. Though the secretion is mainly exocrine small amounts of amylase is found in serum, which seems to originate from the salivary glands.

Amylases↗
PubMed1994

Cyclosporine A inhibits protein-kinase-C-mediated amylase release from isolated rat pancreatic acini.

The present study was performed to characterize a direct influence of cyclosporine A (CsA) on exocrine pancreatic enzyme secretion. CsA inhibited dose-dependently amylase release from isolated rat pancreatic acini in response to carbachol or cholecystokinin octapeptide (CCK-8). A significant reduction in amylase release by 17% was observed at 0.2 mumol/l CsA (p < 0.001) when compared to controls. At 0.2 mmol/l, CsA reduced amylase release in response to both secretagogues by maximally 45%, whereas basal secretion was not affected. CsA had no influence on CCK-8-stimulated increase in intracellular Ca2+ concentrations or amylase release in response to the Ca2+ ionophore A 23187. In contrast, the dose-response curve for amylase secretion induced by the phorbol ester phorbolmyristate-13-acetate was shifted to the right without a reduction of the maximal secretory response. Unexpectedly, vasoactive-intestinal-polypeptide- and secretin-stimulated acinar secretion was not diminished by CsA. In isolated pancreatic lobules exposed to 0.1 mmol/l CsA, amylase release stimulated by cerulein or veratridine was reduced by 26.7 +/- 2 or 28.3 +/- 4%, respectively. CsA had no influence on the displacement of 125I-Bolton-Hunter-labeled CCK-8 from acinar CCK receptors. The ultrastructure of cellular organelles in isolated lobules was not altered after incubation with 0.1 mmol/l CsA for 60 min. Our data suggest that CsA interferes with protein-kinase-C-mediated signal transduction in isolated rat pancreatic acini, without affecting cAMP-dependent signalling.

Amylases↗
PubMedDate not supplied

Identification of amylase crystalloids in cystic lesions of the parotid gland.

OBJECTIVE: To identify alpha-amylase crystalloid formations in parotid specimens obtained by fine needle aspiration. STUDY DESIGN: The study concerned three cases of sialadenitis with crystalloid formation observed between 1993 and 1998. In one of these cases, transmission electron microscopy, mass spectrometry and measurement of amylase activity were used to characterize the nature of the crystalloids. RESULTS: Light microscopy revealed the same crystalloid structure in all three cases. In one case, where the material was saved, a biochemical method made it possible to reveal high amylase activity, while protein electrophoresis and mass spectrometry were used to identify salivary alpha-amylase. CONCLUSION: Crystalloids of salivary alpha-amylase can be identified by May-Grünwald-Giemsa and Papanicolaou stain and can be rapidly confirmed through determination of amylase activity.

Adult↗
PubMed1997

Overexpression of Rab3D enhances regulated amylase secretion from pancreatic acini of transgenic mice.

Rab3D, a member of the ras-related GTP-binding protein Rab family, is localized to secretory granules of various exocrine tissues such as acinar cells of the pancreas, chief cells of the stomach, and parotid and lacrimal secretory cells. To elucidate the function of Rab3D in exocytosis, we have generated transgenic mice that over-express Rab3D specifically in pancreatic acinar cells. Hemagglutinin-tagged Rab3D was localized to zymogen granules by immunohistochemistry, and was shown to be present on zymogen granule membranes by Western blotting; both results are similar to previous studies of endogenous Rab3D. Secretion measurements in isolated acinar preparations showed that overexpression of Rab3D enhanced amylase release. Amylase secretion from intact acini of transgenic mice 5 min after 10 pM cholecystokinin octapeptide (CCK) stimulation was enhanced by 160% of control. In streptolysin-O-permeabilized acini of transgenic mice, amylase secretion induced by 100 microM GTP-gamma-S was enhanced by 150%, and 10 microM Ca2+-stimulated amylase secretion was augmented by 206% of that of the control. To further elucidate Rab3D involvement in stimulus-secretion coupling, we examined the effect of CCK on the rate of GTP binding to Rab3D. Stimulation of permeabilized acini with 10 pM CCK increased the incorporation of radiolabeled GTP into HA-tagged Rab3D. These results indicate that overexpression of Rab3D enhances secretagogue-stimulated amylase secretion through both calcium and GTP pathways. We conclude that Rab3D protein on zymogen granules plays a stimulatory role in regulated amylase secretion from pancreatic acini.

Amylases↗
PubMed1976

A potential screening test for elevated serum amylase levels: preliminary communication.

The use of an amylase-sensitive paper in a screening test for elevated serum amylase levels is described. The paper requires some modification before it can be used as a quantitative amylase assay, but even in its present form it will reliably identify samples with raised amylase levels. In tests with sera received routinely for amylase assay the paper characterised 80% of samples as Normal. Quantitative amylase assay confirmed the results, and thus, even with the present paper, if only the Medium or High sera were sent to the laboratory for full biochemical analysis there would be an 80% decrease in requests.

Amylases↗
PubMed1989

Radioimmunoassay of human pancreatic amylase with monoclonal antibody.

A monoclonal antibody (E-21) was obtained that specifically binds to human pancreatic amylase and shows negligible cross-reaction with human salivary amylase. Using this antibody a radioimmunoassay was developed for pancreatic amylase in human serum. The assay was shown to be sensitive (detectable up to 7 mg/L), reproducible, and specific for pancreatic amylase. In normal subjects, the mean concentration of serum pancreatic amylase determined by this method was 36.3 mg/L with a 95% confidence range of 16.5 to 79.2 mg/L. A good correlation was observed between the concentrations of immunoreactive pancreatic amylase (IR-PA) and enzymatic activities in 20 serum samples (r = 0.97). The concentration of serum IR-PA was below the detectable limit in pancreatectomised patients, and was greatly increased in patients with acute pancreatitis; the latter was accompanied by parallel changes in total enzymic activity. In patients with mumps, the serum IR-PA level was within the normal range whereas the total enzymic activity was elevated.

Amylases↗
PubMed1988

The effect of cholecystokinin-octapeptide, insulin, glucagon, triiodothyronine, and epidermal growth factor on amylase activity in fetal pancreas in vitro.

To evaluate the possible role of various hormones on fetal pancreas development, late gestational fetal rat pancreata (20 days) were cultured in a serum-free medium for 6 days in the presence of cholecystokinin-octapeptide (CCK-8), epidermal growth factor, triiodothyronine, or glucagon with or without dexamethasone. In the absence of any added hormone, the tissue amylase activity declined very rapidly. Epidermal growth factor alone (4.10(-7) M) could not preserve the amylase activity, whereas triiodothyronine (0.1 microM) and glucagon (4 micrograms/ml) had a deleterious effect that was prevented by the addition of DXM (3.10(-6) M). In the presence of CCK-8 (2.10(-11) M) 50 and 30% of the amylase activity was maintained on the 2nd and the 4th day of culture, respectively. The CCK-8 effect was dose dependent and was inhibited by asperlicin (10 microM). The combination of CCK-8 and dexamethasone maintained more than 80% of the amylase activity in the fetal pancreas explants through 4 days of culture. Fetal pancreas cultured in this optimal medium and treated with streptozotocin (10(-7) M) during the 1st day of culture showed a significantly lower tissue amylase activity on the 4th and 6th days than those not treated with streptozotocin. The streptozotocin effect was attenuated when insulin (0.1 U/ml) was added. These data suggest that, in addition to the well-known effect of glucocorticoid on enzyme activities in the fetal pancreas, two additional hormones, CCK and insulin, could play a role in the modulation of pancreatic amylase activity in the fetal rat.

Amylases↗
PubMed1999

Synergistic effects of cAMP- and calcium-mediated amylase secretion in isolated pancreatic acini from cystic fibrosis mice.

We evaluated pancreatic enzyme secretory response to secretagogues (cAMP- and Ca2+-mediating) involved in exocytosis and in chloride channel activation in an exon 10 knockout cystic fibrosis (CF) mouse model. Experiments were performed in isolated pancreatic acini from liquid-fed Cftr-/- mice (5-6 wk of age) and age-matched Cftr+/+ controls fed a solid or liquid diet. BrcAMP and forskolin alone induced higher amylase secretion (% initial amylase content) in the Cftr+/+ acini than carbachol (p < 0.05). Carbachol and BrcAMP or BrcAMP and forskolin, given in combination, produced additive effects on enzyme secretion in the Cftr+/+ acini. Ca2+- and cAMP-mediated amylase secretion in isolated pancreatic acini from the Cftr-/- mice was no different to that observed in the age- and diet-matched Cftr+/+ animals. However, Cftr-/- pancreatic acini showed a significantly greater amylase response to the combination of BrcAMP and carbachol than the sum of the individual responses in separate experiments (p < 0.05). The amylase response was not different in acini from solid-fed or liquid-fed Cftr+/+ controls. In summary, this study suggests that cystic fibrosis transmembrane conductance regulator is not essential for enzyme secretion as evidenced by no reduction in cAMP-mediated amylase secretion in Cftr-/- mice. The results in Cftr+/+ acini suggest pancreatic enzyme secretion is mediated via multiple intracellular pathways acting in parallel and probably converge at a distal step in the secretory process. However, Cftr-/- pancreatic acini exhibited a synergistic secretory response following stimulation by BrcAMP plus carbachol. The enhanced secretory response may partially contribute to the development of pancreatic dysfunction in CF patients by facilitating occlusion of digestive enzymes in the secretory canaliculus of the pancreatic acini.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1983

Effects of porcine gastrin-releasing peptide on amylase release, 2-deoxyglucose uptake, and alpha-aminoisobutyric acid uptake in mouse pancreatic acini.

The effects of synthetic porcine gastrin-releasing peptide (pGRP), a recently isolated gut hormone, were studied in isolated mouse pancreatic acini. pGRP was found to exert direct effects on amylase release, 2-deoxyglucose ( [3H] 2DG) uptake, and alpha-aminoisobutyric acid (AIB) uptake. The stimulatory effect of pGRP on amylase release was significant at 100 pM, and maximal at 1 nM. Higher concentrations of pGRP exerted a smaller stimulatory effect on amylase release. pGRP also increased [3H]2DG uptake, exerting a detectable effect at 300 pM, and a maximal effect at 30 nM. In contrast to its stimulatory effect on amylase release and [3H]2DG uptake, pGRP inhibited AIB uptake. A significant inhibitory effect on AIB uptake occurred at 100 pM, and a maximal inhibitory effect occurred at 3 nM. Dose-response curves of pGRP for amylase release and AIB uptake were found to be biphasic. Bombesin was also found to stimulate amylase release with a biphasic dose-response curve in mouse acini. Both cholecystokinin (CCK) octapeptide and the cholinergic analog carbachol exerted similar effects in isolated mouse acini. However, the effects of pGRP were not inhibited by either dibutyryl cyclic guanosine 3',5'-monophosphate or atropine, whereas the effects of CCK octapeptide were inhibited by dibutyryl cyclic guanosine 3',5'-monophosphate and the effects of carbachol were inhibited by atropine. These results indicate that pGRP can mimic the biological effects of CCK and acetylcholine, but that its actions are probably mediated via a separate class of receptors in mouse acini.

Aminoisobutyric Acids↗
PubMed1993

Glucocorticoid receptor binding site in the mouse alpha-amylase 2 gene mediates response to the hormone.

Amylase gene expression has been shown to be positively regulated by glucocorticoids. Previous reports have suggested that this effect is indirect. We have addressed this question in a mouse exocrine pancreas cell line, 266-6, in which basal level of expression of amylase mRNA is low but inducible by glucocorticoids. In these cells the effect of glucocorticoids is not inhibited by cycloheximide at early time points. Reporter plasmids containing 224 base pairs of mouse amylase 5'-flanking DNA are positively regulated by glucocorticoids in gene transfer experiments. Glucocorticoid receptor purified from rat liver binds to the amylase promoter from position -56 to -33 and at the start of transcription. Site-directed mutation at the upstream position (-47 to -42) eliminates response to glucocorticoids in transient gene transfer experiments. Thus, glucocorticoid regulation of the mouse amylase gene is a direct effect and is mediated via a receptor binding site in the promoter region of the gene. Inhibition of the hormone response by cycloheximide at later time points after induction suggests the additional requirement for a short-lived factor. The DNA binding domain of the glucocorticoid receptor binds to a single site in the amylase promoter as a monomer, suggesting that both receptor binding sites as well as an additional short-lived factor are required to obtain induction.

Animals↗
PubMed1976

Immunohistochemical localization of alpha-amylase in barley aleurone cells.

Alpha-Amylase was localized in aleurone cells of barley using immunohistochemical methods. Anti-alpha-amylase antibody was produced by rabbits immunized with enzyme purified from malt diastase and Himalaya variety barley seeds. Immunoelectrophoresis showed that the antibodies to both antigens were immunologically similar, therefore, they were used interchangeably in the localization of alpha-amylase. Fluorescence of 8-10 mum sections of freeze-substituted and paraffin embedded, gibberellic acid (GA)-treated aleurone tissue incubated with rabbit anti-alpha-amylase IgG and rhodamine-conjugated goat-anti-rabbit IgG is localized in the cytoplasm, the nuclear region and the innermost portion of the cell wall. Cytoplasmic immunofluorescence is not associated with a specific organelle but rather is diffusely distributed. The fluorescence of the nuclear region, however, is intense and in thinner (4-5 mum) sections is associated not with the nucleoplasm but with the nuclear envelope and perinuclear region of the cytoplasm. Fluorescence of the cell wall is confined to the inner boundary of the wall corresponding to the resistant wall layer. The immunofluorescent properties of non-GA-treated cells are quantitatively different; fluorescence of these sections is low and diffuse and is particularly reduced in the nuclear region. Electron microscopy shows that GA-treatment results in the proliferation of endoplasmic reticulum (ER) in the perinuclear region of the cell. We suggest that the alpha-amylase localized by immunofluorescence in the perinuclear region of the cell is localized in this ER produced in response to GA treatment. Immunohistochemical localization of alpha-amylase in cells zonated by centrifugation also suggests that the enzyme is intimately associated with the perinuclear area.

Amylases↗
PubMed1991

Roles of potassium and chloride ions in cAMP-mediated amylase exocytosis from rat parotid acini.

The roles of potassium and chloride ions in cAMP-mediated amylase exocytosis were studied using intact and saponin-permeabilized parotid acini. Cyclic AMP-evoked amylase release from saponin-permeabilized parotid acini decreased markedly when KCl in the incubation medium was isoosmotically replaced by K-glutamate, NaCl, Na-isothionate, or mannitol. Quinidine and barium, K+ channel blockers, clearly inhibited amylase release from the permeabilized acini, but not from intact ones. The chloride channel blocker DPC (diphenylamine-2-carboxylate) also inhibited amylase release, while DIDS (4,4'-diisothiocyanostilben-2,2'-disulfonate) or bumetanide had little effect, if any, on the exocytosis. Hyperosmolarity with mannitol markedly reduced amylase release from permeabilized acini. These results suggest that potassium and chloride ions play important roles in cAMP-mediated amylase exocytosis, and that these ions act on secretory granules inside the acinar cells.

Amylases↗
PubMed1982

Amylase release from parotid glands of hypothyroid rats. I. Altered responsiveness to adrenergic agents.

Effects of adrenergic agents on alpha- and beta-adrenergic receptors of parotid glands from hypothyroid rats were compared with those of euthyroid rats. The sensitivity for amylase release from parotid slices to adrenergic agents did not change even in hypothyroid status because ED50 values for amylase release in both groups were approx. the same: 7 x 10(-8) M for isoproterenol, 4-6 x 10(-6) M for phenylephrine and 10(-5) M for methoxamine. However, the responsiveness of the tissue to those agents which was determined as the maximal amylase release was significantly higher in hypothyroid status than in the euthyroid status. The maximal increases in amylase release in euthyroid and hypothyroid rats were approx. 7.4% and 10.0% of the total in isoproterenol, 3.9% and 7.4% of the total in phenylephrine and 1.3% and 2.7% of the total in methoxamine, respectively. The effect of dibutyryl cyclic AMP mimicked that of isoproterenol, and the responsiveness of the tissue in this case was much higher in the hypothyroid rats than in the euthyroid rats. Furthermore, 10 mM tolbutamide, which completely inhibited the activity of cyclic AMP-dependent protein kinase, blocked isoproterenol-induced amylase release by 66.5% in euthyroid rats, against only 36.3% in hypothyroid rats. These results strongly suggest that the regulation mediated through beta-adrenergic receptors plays a major role in amylase release from rat parotid glands even under hypothyroid status, and the step following cyclic AMP synthesis might, at least in some way, be involved in this regulation.

Adrenergic alpha-Agonists↗
PubMed1984

Inhibitory effect of carbachol on isoproterenol-induced amylase release from isolated rat parotid cells.

The effect of carbachol (CCh) on isoproterenol (ISP)-induced amylase release was investigated using isolated rat parotid cells. CCh (1-100 microM) inhibited ISP (1 microM)-induced amylase release in a dose-dependent manner, whereas CCh alone had a slightly increasing effect on amylase release. Both inhibitory and stimulatory effects of CCh were blocked by atropine (10 microM), and they also disappeared in Ca-free (1 mM EGTA) medium. CCh (10 microM) did not change cyclic AMP levels induced by ISP (1 microM), but significantly inhibited dibutyryl cyclic AMP (1 microM)-induced amylase release. CCh and ISP increased 45Ca2+ uptake in 30 min. Furthermore, 45Ca2+ uptake in the presence of CCh plus ISP increased almost additively. These increasing effects of CCh were abolished by atropine. Calcium ionophore A23187 (10 microM) inhibited ISP-induced amylase release to the level of the release by A23187 alone and considerably increased 45Ca2+ uptake. CCh increased both control and ISP-stimulated effluxes of 45Ca2+ in Ca-free (1 mM EGTA) medium from parotid cells. These results suggest that CCh produces a potent increase in Ca2+ influx from the extracellular medium into parotid cells, and this increase may result in a higher level of cytosolic free Ca2+ which inhibits the ISP-induced amylase release.

Amylases↗
PubMed1985

Forskolin induces supersensitivity of the amylase secretory response of rat parotid tissue.

The stimulatory effect of forskolin on amylase secretion was studied by pretreating rat parotid tissue with forskolin for 10 min, incubating it in medium without forskolin for 10 min, and then treating it with forskolin again. Pretreatment with 10 microM forskolin for 10 min resulted in increased amylase secretion and enhanced accumulation of cyclic AMP in the tissue during the second incubation with forskolin. In the presence of colchicine or vinblastine, the enhancement in cyclic AMP accumulation during the second incubation with forskolin was prevented, but the increased amylase secretion remained unchanged. The increased amylase secretion was counteracted only in the presence of concanavalin A. On the other hand, increased amylase secretion induced by isoproterenol (IPR) pretreatment was counteracted by colchicine, vinblastine, concanavalin A or strychnine. These data suggest that the total amount of cyclic AMP in the tissue does not have any essential role in the supersensitivity of the amylase secretory response, and that the supersensitivity induced by forskolin differs from that induced by IPR.

Amylases↗
PubMed1987

Effect of isoproterenol and forskolin on amylase release from parotid tissue after chronic pilocarpine administration in rats following ligation removal.

The influence of chronic pilocarpine administration on the recovery of the parotid gland from an obstruction was investigated by studying the amylase release induced by secretagogues in rats. Treatment with pilocarpine (5 mg/kg, daily for 7 days) increased amylase release induced by isoproterenol (10(-5) M) or forskolin (10(-5) M) in the parotid tissue of rats after the removal of a 7-day-duct ligation. However, there was no significant difference in the amylase activity of the parotid tissue between pilocarpine-treated rats and control rats. These results suggest that the accelerated recovery of amylase release from parotid tissue in rats chronically treated with pilocarpine may be due to the increased response of amylase release, rather than the increased accumulation of secretory materials in the cells; and furthermore, cyclic AMP-mediated events may be involved in the increased response of amylase release.

Amylases↗
PubMed1998

Rice bifunctional alpha-amylase/subtilisin inhibitor: characterization, localization, and changes in developing and germinating seeds.

A bifunctional alpha-amylase/subtilisin inhibitor (RASI) was purified to electrophoretic homogeneity from rice (Oryza sativa L.) bran. Its molecular mass was 21 kDa by SDS-PAGE and its isoelectric point was 9.05. Purified RASI inhibited subtilisin Carlsberg strongly and inhibited alpha-amylase from germinating rice seeds weakly. It inhibited rice alpha-amylase more than barley alpha-amylase, and the inhibition of rice alpha-amylase was greater at higher pHs. RASI did not inhibit trypsin, chymotrypsin, cucumisin, or mammalian alpha-amylase. The RASI was in the outermost part of the rice grain and its subcellular site seemed to be aleurone particles in aleurone cells. SDS-PAGE and western blotting showed that RASI was synthesized in the late milky stage in developing seeds, and it remained fairly constant during the first 7 days of germination.

Blotting, Western↗