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PubMed2005

Characteristics of the amylase of Arthrobacter psychrolactophilus.

Properties of the extracellular amylase produced by the psychrotrophic bacterium, Arthrobacter psychrolactophilus, were determined for crude preparations and purified enzyme. The hydrolysis of soluble starch by concentrated crude preparations was found to be a nonlinear function of time at 30 and 40 degrees C. Concentrates of supernatant fractions incubated without substrate exhibited poor stability at 30, 40, or 50 degrees C, with 87% inactivation after 21 h at 30 degrees C, 45% inactivation after 40 min at 40 degrees C and 90% inactivation after 10 min at 50 degrees C. Proteases known to be present in crude preparations had a temperature optimum of 50 degrees C, but accounted for a small fraction of thermal instability. Inactivation at 30, 40, or 50 degrees C was not slowed by adding 20 mg/ml bovine serum albumin or protease inhibitor cocktail to the preparations or the assays to protect against proteases. Purified amylase preparations were almost as thermally sensitive in the absence of substrate as crude preparations. The temperature optimum of the amylase in short incubations with Sigma Infinity Amylase Reagent was about 50 degrees C, and the amylase required Ca(+2) for activity. The optimal pH for activity was 5.0-9.0 on soluble starch (30 degrees C), and the amylase exhibited a K (m) with 4-nitrophenyl-alpha-D-maltoheptaoside-4,6-O-ethylidene of 120 microM at 22 degrees C. The amylase in crude concentrates initially hydrolyzed raw starch at 30 degrees C at about the same rate as an equal number of units of barley alpha-amylase, but lost most of its activity after only a few hours.

Amylases↗
PubMed2007

Cloning and characterization of a maltotriose-producing alpha-amylase gene from Thermobifida fusca.

The gene (tfa), encoding a maltotriose-producing alpha-amylase from Thermobifida fusca NTU22, was cloned, sequenced and expressed in Escherichia coli. The gene consists of 1,815 base pairs and encodes a protein of 605 amino acids. The base composition of the tfa coding sequence is 69% G+C and the protein has a predicted pI value of 5.5. The deduced amino acid sequence of the tfa amylase exhibited a high degree of similarity with amylases from Thermomonospora curvata and Streptomyces amylases. The purified amylase could be detected as a single band of about 65 kDa by SDS-polyacrylamide gel electrophoresis and this agrees with the predicted size based on the nucleotide sequence. The optimal pH and temperature of the purified amylase were 7.0 and 60 degrees C, respectively. The properties of purified amylase from the E. coli transformant are similar to that of an amylase purified from the original T. fusca NTU22.

Amino Acid Sequence↗
PubMed1991

Effects of prolonged parotid duct ligation, parotidectomy and acute hepatitis of rats on amylase activity.

Amylase activity in the parotid gland was extremely reduced (to 2.4 per cent) by prolonged duct ligation but that in the pancreas and serum as similar to controls. The serum amylase activity of parotidectomized rats was remarkably reduced within a week of surgery, but recovered to approximately the previous level in 4 weeks. The amylase activities in the pancreas and liver were not different between control and parotidectomized rats. The serum amylase activity of rats with acute hepatitis (1 day after administration of D-galactosamine) decreased to 18.5 per cent compared with controls; however, the activity recovered to its original level after 4-7 days. There was no pancreatic amylase in the serum either of parotidectomized rats or those with acute hepatitis. These observations show that the parotid glands may not be the only source of serum amylase. Serum amylase is mainly derived from the parotid gland, but liver may contribute to serum amylase in compensation for the parotid glands.

Acute Disease↗
PubMed1984

Structure studies of amylose-V complexes and retrograded amylose by action of alpha amylases, and a new method for preparing amylodextrins.

Human-salivary, porcine-pancreatic, and Bacillus subtilis alpha amylases were used to study the structure of amylose-V complexes with butyl alcohol, tert-butyl alcohol, 1,1,2,2-tetrachloroethane, and 1-naphthol, and of retrograded amylose. Alpha amylase hydrolyzes the amorphous, folding areas on the surfaces of the lamella of packed helices, with the formation of resistant, amylodextrin fragments. Their degree of polymerization (d.p.) corresponds to the diameter of the helices and the folding length of the chain. The resistant fragments were fractionated on a column of Bio-Gel A-0.5m. Gel filtration of human-salivary and porcine-pancreatic alpha amylase hydrolyzates gave resistant fragments whose peak fractions, i.e., the three pooled fractions from the gel-filtration column with the highest amount of carbohydrate, had a d.p. of 75 +/- 4 for the amylose complex with butyl alcohol, 90 +/- 3 for those with tert-butyl alcohol and tetrachloroethane, and 123 +/- 2 for that with 1-naphthol. These d.p. values correspond to helices of six residues per turn with a folding length of 10 nm, seven residues per turn with a folding length of 10 nm, and eight residues per turn with a folding length of 12 nm (or nine residues per turn with a folding length of 10 nm), respectively. Acid hydrolysis of retrograded amylose gave a resistant fragment having an average d.p. of 32, human-salivary and porcine-pancreatic alpha amylases gave a resistant fragment of d.p. 43, and Bacillus subtilis alpha amylase gave a resistant fragment of d.p. 50. A structure for retrograded amylose is proposed in which there are crystalline, double-helical regions that are 10 nm long, interspersed with amorphous regions. The amorphous regions are hydrolyzed by acid and by alpha amylases, leaving the crystalline regions intact. The differences in the sizes of the resistant amylodextrins depend on the differences in the specificities of the hydrolyzing agents: acid hydrolyzes right up to the edge of the crystalline region, whereas the alpha amylases hydrolyze up to some point several D-glucosyl residues away from the crystalline region, leaving "stubs" on the ends of the amylodextrins whose sizes are dependent on the sizes of the binding sites of the individual alpha amylases.(ABSTRACT TRUNCATED AT 400 WORDS)

Alcohols↗
PubMed1990

Enzyme immunoassay for human pancreatic amylase.

An enzyme immunoassay (EIA) for human pancreatic amylase has been developed for the detection of human serum amylase content. Our monoclonal antibody is highly specific for human pancreatic amylase; it cross reacted negligibly with the salivary isoenzyme. We developed a solid phase enzyme immunoassay for determination of pancreatic amylase in human serum with this antibody. The assay required 20 microL of serum and the standard curve was linear to at least 1000 ng/mL of pancreatic amylase. Inter- and intra-assay CVs were less than 10%. The results obtained by the EIA correlated well with those determined by the conventional electrophoretic method. In normal subjects, the mean concentration of serum pancreatic amylase determined by the EIA was found to be 92.3 +/- 26.1 ng/mL (mean +/- SD). The EIA we describe is useful for directly determining pancreatic amylase in human serum. Specifically distinguishing pancreatic from salivary amylase may have considerable clinical value.

Amylases↗
PubMed1988

Effect of AA861, a 5-lipoxygenase inhibitor, on amylase secretion from rat pancreatic acini.

We have examined the effects of 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA861), a selective inhibitor of 5-lipoxygenase, on the action of cholecystokinin (CCK) and other secretagogues in the stimulation of amylase secretion from dispersed rat pancreatic acini. AA861 inhibited amylase secretion caused by CCK, carbamylcholine (carbachol), bombesin or calcium ionophore A23187 but failed to affect amylase secretion by vasoactive intestinal peptide or 12-O-tetradecanoyl-phorbol 13-acetate. Inhibition by AA861 of CCK or carbachol-induced amylase secretion was confined to the relatively lower concentrations of these secretagogues. AA861 did not inhibit receptor binding of CCK or alter the cellular calcium mobilization induced by CCK. In kinetic studies, AA861 was effective only on amylase secretion from pancreatic acini incubated with CCK for more than 5 min. Indomethacin, a known inhibitor of cyclooxygenase, did not affect the amylase secretion caused by all secretagogues used. These results indicate that the 5-lipoxygenase pathway of arachidonate metabolism may be involved in the actions of calcium-dependent secretagogues of amylase secretion in rat dispersed pancreatic acini, especially for sustaining stimulation of amylase secretion by CCK.

Amylases↗
PubMed1992

Relationship between cytosolic Ca2+ concentration and amylase release in rat parotid acinar cells following muscarinic stimulation.

Carbachol (CCh), a muscarinic-cholinergic agonist, increased both cytosolic free calcium concentration ([Ca2+]i) and amylase release in rat parotid acinar cells or acini in a dose-dependent manner. Treatment of acinar cells with the intracellular Ca2+ antagonist, 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), or the intracellular Ca2+ chelator, 1,2-bis(O-aminophenoxy)ethane-N,N,N'N'-tetraacetic acid (BAPTA), strongly attenuated the increases in [Ca2+]i evoked by CCh, but amylase release from acini was not significantly suppressed by the treatment with TMB-8 or BAPTA. Low concentrations (0.02-0.5 microM) of ionomycin, a Ca2+ ionophore, caused increases in [Ca2+]i comparable to those induced by CCh, but the same concentrations had only a little effect on amylase release. The protein kinase C activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), stimulated amylase release in quantities similar to those induced by CCh, although TPA alone did not cause any change in [Ca2+]i. Combined addition of TPA and ionomycin potentiated only modestly amylase release stimulated by TPA alone. Staurosporine, a protein kinase C-inhibitor, similarly inhibited both the CCh- and TPA-induced amylase release. These results suggest that an increase in [Ca2+]i elicited by CCh does not play an essential role for inducing amylase release in rat parotid acini. Amylase release by muscarinic stimulation may be mediated mainly by activation of protein kinase C.

Alkaloids↗
PubMed1993

Occupation of low-affinity cholecystokinin (CCK) receptors by CCK activates signal transduction and stimulates amylase secretion in pancreatic acinar cells.

Based on the effects of monensin on binding of 125I-CCK-8 and its lack of effect on CCK-8-stimulated amylase secretion we previously proposed that pancreatic acinar cells possess three classes of CCK receptors: high-affinity receptors, low-affinity receptors and very low-affinity receptors [1]. In the present study we treated pancreatic acini with carbachol to induce a complete loss of high-affinity CCK receptors and then examined the action of CCK-8 on inositol trisphosphate IP3(1,4,5), cytosolic calcium and amylase secretion in an effort to confirm and extend our previous hypothesis. We found that first incubating pancreatic acini with 10 mM carbachol decreased binding of 125I-CCK-8 measured during a second incubation by causing a complete loss of high-affinity CCK receptors with no change in the low-affinity CCK receptors. Carbachol treatment of acini, however, did not alter the action of CCK-8 on IP3(1,4,5), cytosolic calcium or amylase secretion or the action of CCK-JMV-180 on amylase secretion or on the supramaximal inhibition of amylase secretion caused by CCK-8. The present findings support our previous hypothesis that pancreatic acinar cells possess three classes of CCK receptors and suggest that high-affinity CCK receptors do not mediate the action of CCK-8 on enzyme secretion, that low-affinity CCK receptors may mediate the action of CCK on cytosolic calcium that does not involve IP3(1,4,5) and produce the upstroke of the dose-response curve for CCK-8-stimulated amylase secretion and that very low-affinity CCK receptors mediate the actions of CCK on IP3(1,4,5) and cytosolic calcium and produce the downstroke of the dose-response curve for CCK-8-stimulated amylase secretion. Moreover, CCK-JMV-180 is a full agonist for stimulating amylase secretion by acting at low-affinity CCK receptors and is an antagonist at very low-affinity CCK receptors.

Amylases↗
PubMed1991

Lowering of pancreatic amylase activity induced by cold exposure, fasting and adrenalectomy in rats.

1. Alteration of amylase activity in the pancreas was studied in rats under different stressful situations. 2. Cold-exposed rats had reduced amylase activity, hypertrophy of adrenal glands, and lowered plasma insulin and glucose. 3. In fasted rats, amylase activity decreased and plasma insulin and glucose lowered. 4. Immobilized animals failed to produce the reduced amylase activity, despite existence of higher plasma corticosterone. 5. Adrenalectomy caused reduction of amylase activity accompanied by decreases in plasma insulin and glucose. 6. Glucocorticoid hormone is not correlated with suppression of amylase synthesis. The lowered amylase activity might involve changes in glycolytic flux and/or suppression of amylase synthesis by insulin deficiency.

Adrenal Glands↗
PubMed1975

Amylase secretion by rabbit parotid gland. Role of cyclic AMP and cyclic GMP.

Amylase secretion and changes in the levels of cyclic AMP and GMP were studied in rabbit parotid gland slices incubated in vitro with a variety of neurohumoral transmitters, their analogs and inhibitors. Cyclic GMP levels increased 8-fold 5 min after exposure to carbachol (10(-4) M), without a change in cyclic AMP levels; amylase output also rose. These effects were completely inhibited by muscarinic blockade with atropine, but were unaffected by alpha-adrenergic blockade with phenoxybenzamine. Epinephrine (4 - 10(-5) M) produced a rapid increase in the levels of both cyclic nucleotides and in amylase release. The increase in cyclic GMP level was inhibited by previous exposure of the slices to phenoxybenzamine, while the cyclic AMP rise was prevented by the beta-blocking agent, propranolol. Pure alpha-adrenergic stimulation with methoxamine (4 - 10(-4) M) produced modest elevations in cyclic GMP content and amylase output, effects blocked by pre-treatment of slices with either atropine or phenoxybenzamine. At a concentration of 4 - 10(-6) M, isoproterenol (a beta-agonist) failed to affect cyclic GMP levels, but promptly stimulated increases in cyclic AMP levels, and after a short lag, amylase secretion. At a higher dose (4 - 10(-5) M) isoproterenol produced elevations in the levels of both nucleotides. The carbachol-induced effects on cyclic GMP content and amylase release were greatly potentiated by the addition of isoproterenol (4 - 10(-6) M). These data strongly suggest that cholinergic muscarinic agonists and alpha-adrenergic agonists stimulate amylase output in rabit parotid gland by mechanisms involving cyclic GMP. The atropine-sensitive intracellular events effected by alpha-stimulation may be dependent upon endogenous generation of acetylcholine. Both cyclic nucleotides seem to be required for the early rapid secretion of amylase. The unique responses achieved by the combination of carbachol and isoproterenol suggest that isoproterenol may increase the sensitivity of this tissue to the effects of cholinergic stimuli.

Amylases↗
PubMed1992

Enzymic activity of salivary amylase when bound to the surface of oral streptococci.

The enzymatic activity of salivary amylase bound to the surface of several species of oral streptococci was determined by the production of acid from starch and by the degradation of maltotetraose to glucose in a coupled, spectrophotometric assay. Most strains able to bind amylase exhibited functional enzyme on their surface and produced acid from the products of amylolytic degradation. These strains were unable to utilise starch in the absence of salivary amylase. Two strains failed to produce acid from starch, despite the presence of functional salivary amylase, because they could not utilise maltose. Strains that could not bind salivary amylase failed to produce acid from starch. In no case was all the bound salivary amylase active, and two strains of Streptococcus mitis which bound amylase did not exhibit any enzyme activity on their cell surface. The ability to bind amylase may confer a survival advantage on oral bacteria which inhabit hosts that consume diets containing starch.

Acids↗
PubMed1989

The human alpha-amylase multigene family consists of haplotypes with variable numbers of genes.

Polymorphic amylase protein patterns have suggested the presence in the human genome of various haplotypes encoding these allozymes. To investigate the genomic organization of the human alpha-amylase genes, we isolated the pertinent genes from a cosmid library constructed of DNA from an individual expressing three different salivary amylase allozymes. From the restriction maps of the overlapping cosmids and a comparison of these maps with the restriction enzyme patterns of DNA from the donor and family members, we were able to identify two haplotypes consisting of very different numbers of salivary amylase genes. The short haplotype contains two pancreatic genes (AMY2A and AMY2B) and one salivary amylase gene (AMY1C), arranged in the order 2B-2A-1C, encompassing a total length of approximately 100 kb. The long haplotype spans about 300 kb and contains six additional genes arranged in two repeats, each one consisting of two salivary amylase genes (AMY1A and AMY1B) and a pseudogene lacking the first three exons (AMYP1). The order of the amylase genes within the repeat is 1A-1B-P1. All genes are in a head-to-tail orientation except AMY1B, which has the reverse orientation with respect to the other genes. Analysis of somatic cell hybrids confirmed the presence of these short and long haplotypes. Furthermore, we present evidence for the existence of additional haplotypes in the human population and propose a general model for the evolution of the human alpha-amylase multigene family. A general designation 2B-2A-(1A-1B-P)n-1C can describe these haplotypes, n being 0 and 2 for the short and the long haplotypes presented in this paper, respectively.

Biological Evolution↗
PubMed2004

Effect of psychological stress on the salivary cortisol and amylase levels in healthy young adults.

OBJECTIVE: Saliva sampling has the advantage that it is non-invasive, making multiple sampling easy and stress free. We examined the effects of psychological stressor and soother on the salivary cortisol and amylase levels in young adults, and compared the characteristics of these parameters. DESIGN: The subjects completed the trait version of State-Trait Anxiety Inventory (STAI) to assess the predisposition to personal anxiety. The video of corneal transplant surgery was served as the stressor for 15 min. A scenic beauty video viewing was also used as the soother. Unstimulated whole saliva was collected every 3 min throughout the session. RESULTS: The amylase level was significantly increased just after the beginning of the stressful video viewing, and immediately returned to the pre-stress level just after the end of the video viewing. The cortisol level was also increased, but to a lesser extent compared with that of amylase. The latency time to the peak level for cortisol was longer than that of amylase. The carry-over effect was not observed in the amylase response but was in cortisol. Although the correlation between the amylase level and the STAI score was highly significant, cortisol level did not. In addition, soothing video viewing significantly decreased the amylase level, but did not affect the cortisol level. CONCLUSION: Salivary amylase level was more significantly increased and reacted more rapidly than cortisol by psychological stressor, suggesting that it is a better index of stress. Furthermore, it is suggested that the enzyme is a soothing or relaxation index.

Adult↗
PubMed2006

Purification, characterization, and synergistic action of phytate-resistant alpha-amylase and alpha-glucosidase from Geobacillus thermodenitrificans HRO10.

The alpha-amylase (1, 4-alpha-d-glucanohydrolase; EC 3.2.1.1) and alpha-glucosidase (alpha-d-glucoside glucohydrolase; EC 3.2.1.20) secreted by Geobacillus thermodenitrificans HRO10 were purified to homogeneity (13.6-fold; 11.5% yield and 25.4-fold; 32.0% yield, respectively) through a series of steps. The molecular weight of alpha-amylase was 58kDa, as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The alpha-amylase activity on potato starch was optimal at pH 5.5 and 80 degrees Celsius. In the presence of Ca(2+), the alpha-amylase had residual activity of more than 92% after 1h of incubation at 70 degrees Celsius. The alpha-amylase did not lose any activity in the presence of phytate (a selective alpha-amylase inhibitor) at concentrations as high as 10mM, rather it retained 90% maximal activity after 1h of incubation at 70 degrees Celsius. EGTA and EDTA were strong inhibitory substances of the enzyme. The alpha-amylase hydrolyzed soluble starch at 80 degrees Celsius, with a K(m) of 3.05mgml(-1) and a V(max) of 7.35Uml(-1). The molecular weight of alpha-glucosidase was approximately 45kDa, as determined by SDS-PAGE. The enzyme activity was optimal at pH 6.5-7.5 and 55 degrees Celsius. Phytate did not inhibit G. thermodenitrificans HRO10 alpha-glucosidase activity, whereas pCMB was a potent inhibitor of the enzyme. The alpha-glucosidase exhibited Michaelis-Menten kinetics with maltose at 55 degrees Celsius (K(m): 17mM; V(max): 23micromolmin(-1)mg(-1)). Thin-layer chromatography studies with G. thermodenitrificans HRO10 alpha-amylase and alpha-glucosidase showed an excellent synergistic action and did not reveal any transglycosylation catalyzed reaction by the alpha-glucosidase.

Bacillaceae↗
PubMed2006

Salivary alpha-amylase response to competition: relation to gender, previous experience, and attitudes.

This study examined individual differences in salivary alpha-amylase response to competition in relation to gender, previous experience, behavior, attitudes, and performance. Participants were 42 (21 women) members of a collegiate crew team. Saliva samples were collected before, 20- and 40-min post-ergometer competition and at the same times on a non-competition day for comparison. Samples were assayed for salivary biomarkers of sympathetic nervous system (alpha-amylase) and hypothalamic-pituitary-adrenal axis (cortisol) activity. Behavioral assessments included self-reports of dominance, competitiveness, bonding with teammates, competition-related strategic thinking, and performance. On average, salivary alpha-amylase increased 156% in response to the ergometer competition. By comparison, cortisol increased 87% across the same time period. Salivary alpha-amylase was higher across the competition for varsity than for novice athletes, and was positively associated with performance and interest in team-bonding. Regression analyses revealed that alpha-amylase reactivity explained individual differences in dominance and team bonding above and beyond that associated with cortisol reactivity, and that joint inactivation in alpha-amylase and cortisol reactivity to competition (low-low) was associated with high perceived dominance. The findings are among the first to integrate salivary alpha-amylase into the study of competition and reveal that intra-individual change in alpha-amylase may be influenced by a confluence of factors that include contextual, behavioral, and psychological factors and processes.

Adolescent↗
PubMed2002

Functional mimicry between anti-Tendamistat antibodies and alpha-amylase.

A proteinaceous inhibitor of alpha-amylase, Tendamistat, was evaluated as an immunogen to induce antibodies that mimic the enzyme activity and to investigate a new strategy to produce catalytic antibodies. Anti-Tendamistat polyclonal antibodies (pAbs) were shown to cross-react with acarbose, a strong carbohydrate inhibitor of alpha-amylases, and the alpha-amylase carbohydrate substrates, maltotetraose and maltoheptaose. Catalytic features of pAbs were characterized after denaturing natural serum alpha-amylase by treatment at pH 10 and in the presence of EDTA. A significant residual alpha-amylase activity was detected and associated with the IgG fraction, demonstrating that some antibodies behave as a functional mimic of natural amylase. Such antibodies, which behave as an "internal image" of the alpha-amylase, were used as immunogens to elicit anti-idiotype antibodies. It was demonstrated that the anti-idiotype antiserum contains a significant amount of antibodies that bind to porcine pancreatic amylase, which shows that they contain structural information from the original hapten, Tendamistat.

Acarbose↗
PubMed2002

Protease-activated receptor-2 (PAR-2) in the pancreas and parotid gland: Immunolocalization and involvement of nitric oxide in the evoked amylase secretion.

Protease-activated receptor-2, a G protein-coupled receptor activated by serine proteases such as trypsin, tryptase and coagulation factors VIIa and Xa, modulates pancreatic and salivary exocrine secretion. In the present study, we examined the distribution of PAR-2 in the pancreas and parotid gland, and characterized the PAR-2-mediated secretion of amylase by these tissues in vivo. Immunohistochemical analyses using the polyclonal antibody against rat PAR-2 clearly showed abundant expression of PAR-2 in rat pancreatic and parotid acini. The PAR-2 agonist SLIGRL-NH2, administered intraperitoneally (i.p.) at 1-10 micromol/kg and 1.5-15 micromol/kg, in combination with amastatin, an aminopeptidase inhibitor, facilitated in vivo secretion of pancreatic and salivary amylase in a dose-dependent manner, respectively, in the mouse. The PAR-2-mediated secretion of pancreatic amylase was abolished by pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor. The secretion of salivary amylase in response to the PAR-2 agonist at a large dose, 15 micromol/kg, but not at a smaller dose, 5 micromol/kg, was partially reduced by L-NAME. Pretreatment with capsaicin for ablation of the sensory neurons did not modify the PAR-2-mediated secretion of pancreatic and salivary amylase in the mouse. In conclusion, our study demonstrates expression of PAR-2 in rat pancreatic acini as well as parotid acini and indicates that nitric oxide participates in the PAR-2-mediated in vivo secretion of pancreatic amylase, and, to a certain extent, of salivary amylase, although capsaicin-sensitive sensory neurons, known to be activated by PAR-2, are not involved in the evoked pancreatic or salivary amylase secretion.

Amino Acid Sequence↗
PubMed1999

Nitric oxide modulates salivary amylase and fluid, but not epidermal growth factor secretion in conscious rats.

The involvement of the L-arginine/NO pathway in the control of salivary fluid, amylase and epidermal growth factor (EGF) secretion was investigated in conscious rats. For the collection of saliva, an oesophageal cannula was implanted. To obtain steady secretion, submaximal carbachol background infusion was given. Different treatments included NO synthase inhibitor N(G)-nitro-L-arginine (NOLA; with or without phentolamine, propranolol), L-arginine, D-arginine and NO donor 3-morpholinosydnonimine (SIN-1) administration. Volume, amylase activity and EGF output in the secreted fluid were determined in 30 min mixed saliva samples. Carbachol infusion alone produced a modest, sustained salivary fluid and amylase secretion. NOLA (30 mg/kg) further increased both fluid (p<0.001) and amylase outputs (p<0.001). These latter effects were prevented by L-arginine but not by D-arginine or by phentolamine. Propranolol administration decreased both fluid and amylase secretion below the carbachol plateau, and NOLA did not modify this suppressed secretory rate. SIN-1 did not alter either volume or amylase secretion. Interestingly, NOLA given without carbachol did not modify salivation. Neither carbachol nor NOLA changed salivary EGF output. The present results suggest that the L-arginine/NO pathway has a modulatory role in the cholinergic control of salivary amylase secretion, but not in EGF output. The mechanisms of inhibitory action of NO on salivary fluid and amylase secretion remain to be identified.

Amylases↗