Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Partially purified beta cell monolayer cultures were prepared from the pancrease of neonatal Wistar rats by dissociating the cells with a trypsin-collagenase solution. The cultures were grown in medium 199 containing a 10% fetal calf serum and 100 or 300 mg/100 ml glucose. Insulin release from the primary cultures during 12 days was 15 to 20 microunit/culture/day when the cells were grown in the medium containing 300 mg/100 ml glucose. When glucose concentration in the medium was decreased from 300 to 100 mg/ml insulin release fell to 2--5 microunit/culture/day. Theophylline stimulated insulin release in a short-time experiment. Transplantation of a 6--8-day culture in diabetic rats reduced the blood glucose concentration for 1 to 2 days.
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PMID:[Monolayer culture of pancreatic beta cells of newborn rats: Insulin secretion in vitro and attempt at beta-cell transplantation in experimental diabetes]. 15 May 94

A method for measuring cAMP in frog skin epithelium was developed. The epithelia were isolated after collagenase-treatment. cAMP was extracted by boiling water and the extract was purified on dry Al2O3. The change with time of the cAMP level after addition of arginine vasotocin (AVT) was studied. The hormone caused a rapid increase in cAMP level with a maximum after 3-5 min, whereafter the cAMP level declined. Incubation with AVT made the epithelia refractory to a second dose of AVT, which indicates that the decline in cAMP level was caused by a feedback mechanism and not by inactivation of the hormone. cAMP appeared evenly distributed in all cell-layers of the epithelia both before and after stimulation with AVT. Theophylline caused a rapid increase in the cAMP level, which remained elevated for at least 45 min. Addition of the ionophore A23187 or of filipin had no effect on the cAMP level. However, in the presence of theophylline, A23187 enhanced the cAMP level, whereas filipin had no effect. Therefore the involvement of cAMP in the action of A23187 has to be considered.
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PMID:Effects of the antidiuretic hormone, arginine vasotocin, theophylline, filipin and A23187 on cyclic AMP in isolated frog skin epithelium (Rana temporaria). 20 96

We tested the hypothesis that the adenylate cyclase system and Na+, K(+)-ATPase are reciprocally related in rat pancreatic islets. We studied the effect of theophylline, caffeine, and dibutyryl cyclic AMP on Na+, K(+)-ATPase activity in a membrane preparation from collagenase-isolated rat islets. Theophylline, caffeine, or dibutyryl cyclic AMP, in concentrations of 1 mM, all inhibited Na+, K(+)-ATPase activity (44,62, and 43%, respectively). Kinetic analysis indicated that theophylline and dibutyryl cAMP inhibit Na+, K(+)-ATPase by different mechanisms; theophylline decreased Vmax and decreased apparent Km (ATP), whereas dibutyryl cAMP decreased Vmax and increased apparent Km (ATP). Similar inhibition of Na+, K(+)-ATPase by theophylline or dibutyryl cAMP was noted in a particulate fraction from rat kidney and in a purified porcine brain Na+, K(+)-ATPase preparation. The adenylate cyclase system and Na+, K(+)-ATPase may act reciprocally in pancreatic islets and in other tissues. In the beta cell this relationship may be essential in coordinating consumption of ATP in the stimulated, as opposed to the rest, state.
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PMID:Relationships between adenylate cyclase and Na+, K(+)-ATPase in rat pancreatic islets. 215 93

This study was undertaken to investigate the long-term effects of different substrates, in particular glucose, on the regulation of islet RNA metabolism and the relationship of this regulation to the metabolism and insulin production of the islet B-cell. For this purpose collagenase-isolated mouse islets were used either in the fresh state or after culture for 2 or 5 days in RPMI 1640 plus 10% calf serum supplemented with various test compounds. Islets cultured with 16.7 mM glucose contained more RNA than those cultured with 3.3 mM glucose. Culture of islets in glucose at low concentrations inhibited glucose-stimulated RNA synthesis and this inhibitory effect was reversed by prolonged exposure to high glucose concentrations. Culture with 10 mM leucine and 3.3 mM glucose or with 10 mM 2-ketoisocaproate and 3.3 mM glucose increased the total RNA content of islets as compared to that of islets cultured with 3.3 mM glucose alone. Islets cultured with 5 mM theophylline maintained a high RNA content in the presence of 3.3 mM glucose. Theophylline also increased the islet RNA content when added together with 16.7 mM glucose, as compared to 16.7 mM glucose alone. Theophylline probably exerted this effect by decreasing the rate of RNA degradation. Changes in islet RNA metabolism showed a close correlation to changes in islet total protein biosynthesis, whereas islet (pro)insulin biosynthesis and insulin release exhibited different glucose-dependency patterns. The response of islet oxygen uptake to glucose was similar to that of islet RNA and protein biosynthesis. It is concluded that the RNA content of the pancreatic islets is controlled at the levels of both synthesis and degradation. Glucose stimulates the RNA synthesis and inhibits its degradation. Moreover, the results suggest that regulation of RNA synthesis may be mediated through islet metabolic fluxes and the cAMP system.
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PMID:Regulation of RNA metabolism in relation to insulin production and oxidative metabolism in mouse pancreatic islets in vitro. 242 38

With the use of a collagenase dispersion technique, cells were isolated from the lamina propria of the human small and large intestine. The cell suspensions contained 8% mast cells, which on average contained 1 to 2 pg of histamine/cell. With the use of histochemical procedures based upon fixative sensitivity and dye binding, which identify functionally distinct mast cell subtypes in the rat, dispersed human intestinal mast cells contained approximately equal proportions of two histochemical subtypes analogous to those in the rat. Whether these are functionally distinct as in the rat remains to be determined. The histochemically mixed mast cell populations from the human intestinal mucosa secreted histamine in a dose- and energy-dependent manner in response to anti-IgE and A23187, but not 48/80. Theophylline, doxantrazole, quercetin, and salbutamol all significantly inhibited anti-IgE-induced histamine secretion by human intestinal mast cells, but cromolyn sodium and the experimental antisecretory drugs, nedocromil sodium and FPL 52694, did not inhibit histamine secretion by the mast cell mixture to a statistically significant extent. Cromolyn sodium inhibited histamine secretion by 15 to 30%, and whether this reflected inhibition of one of the two histochemical mast cell subtypes to a greater extent than the other or all the cells to a minimal degree remains to be established. Control investigations of the intestinal cell isolation procedure indicated that these qualities did not reflect effects of the cell dispersal procedure. Further characterization and analysis of intestinal mast cells is essential to determine if functionally distinct mast cell subtypes exist in human tissues.
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PMID:Mast cells from the human intestinal lamina propria. Isolation, histochemical subtypes, and functional characterization. 243 1

Although both methacholine (MCh)- and A23187-induced sweat secretion are known to be strictly dependent on extracellular Ca2+, the role of intracellular calcium concentration ([Ca2+]i) in eccrine sweating has not been clarified. Partially purified eccrine secretory cells were prepared from 400 to 600 isolated secretory coils of monkey sweat glands by serial collagenase digestion and Percoll gradient centrifugation. The quin2 method was used for semiquantitative determination of [Ca2+]i, MCh increased [Ca2+]i in a dose-dependent, reversible, and pharmacologically specific manner (from the resting [Ca2+]i of 80-320 nM) but failed to increase [Ca2+]i in a Ca2+-free medium. A23187 (10(-7) M) increased [Ca2+]i to approximately 900 nM. Theophylline (TH), isoproterenol (ISO), and forskolin (FK) had no effect on the resting [Ca2+]i but, in combination, attenuated the effect of subsequently added MCh and A23187. A23187 at 10(-7) M failed to stimulate sweat secretion or CO2 production in vitro from the quin2-loaded intact isolated sweat glands and dispersed sweat secretory cells, respectively. The observed dissociation between the increase in [Ca2+] may suggest either that MCh stimulation induces some unknown excitatory signal in addition to a rise in [Ca2+] or that A23187-induced Ca2+ influx into the secretory cells is much lower in undissociated sweat glands.
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PMID:Relationship between quin2-determined cytosolic [Ca2+] and sweat secretion. 283 26

The objectives of this study were to establish a suitable and validated in vitro bioassay of piscine gonadotropins (GTHs) by using a carp testis androgen production system and to compare the androgenic responses in such an assay to gonadotropins from various vertebrate species. The testes from mature carp with gonadosomatic indices of 8-30% were used. Androgen production was first compared with respect to methods for preparation of the carp testis (sliced, minced, homogenized, and collagenase-dispersed testis preparations). The time course of androgen formation, the effects of xanthine and theophylline, and other factors on androgen production also were investigated. Theophylline was more effective than xanthine in potentiation of gonadotropin-evoked androgen formation by carp testis. The testis preparations were incubated in medium 199 (pH 7.40) containing 2 mM theophylline with shaking at 100 cycles/min at 25 degrees C for 4 hr. Homogenized testis preparations had limited ability for androgen production, while sliced, minced, and minced-collagenase-dispersed testis preparations were highly responsive to gonadotropins for androgen production. The minced testis preparation, utilizing 100 mg/ml incubation medium per vial, was chosen as the standard incubation procedure in this study. The minced testis androgen production assay was highly sensitive to gonadotropins from several piscine species (silver carp, common carp, and salmon), and all these GTHs produced parallel dose-related androgen production curves. Mammalian GTHs were also capable of promoting androgen formation by carp testis, but they were much less potent than were piscine GTHs. Pregnant mares' serum gonadotropin (PMSG) was more effective than human chorionic gonadotropin (hCG) in evoking carp testis androgen production.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Species variation of gonadotropic activity in an in vitro assay measuring androgen formation by carp (Cyprinus carpio) testis with special reference to bioassay of piscine gonadotropins. 377 Apr 34

1. Insulin secretion was studied in isolated islets of Langerhans obtained by collagenase digestion of rat pancreas. In addition to responding to glucose and mannose as do whole pancreas and pancreas slices in vitro, isolated rat islets also secrete insulin in response to xylitol, ribitol and ribose, but not to sorbitol, mannitol, arabitol, xylose or arabinose. 2. Xylitol and ribitol readily reduce NAD(+) when added to a preparation of ultrasonically treated islets. 3. Adrenaline (1mum) inhibits the effects of glucose and xylitol on insulin release. Mannoheptulose and 2-deoxy-glucose, however, inhibit the response to glucose but not that to xylitol. 4. The intracellular concentration of glucose 6-phosphate is increased when islets are incubated with glucose but not with xylitol, suggesting that xylitol does not promote insulin release by conversion into glucose 6-phosphate. 5. Theophylline (5mm) potentiates the effect of 20mm-glucose on insulin release from isolated rat islets of Langerhans, but has no effect on xylitol-mediated release. These results indicate that xylitol does not stimulate insulin release by alterations in the intracellular concentrations of cyclic AMP. 6. A possible role for the metabolism of hexoses via the pentose phosphate pathway in the stimulation of insulin release is discussed.
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PMID:Pentitols and insulin release by isolated rat islets of Langerhans. 487 33

The adenosine analogue 765-21 (10 micrograms/kg intravenously), substituted at the 5'-position, caused a sustained increase in plasma glucose and a decrease in plasma free fatty acid concentrations in conscious dogs. Concomitantly, plasma glucagon levels rose threefold. Changes in plasma insulin concentration were relatively small and of no statistical significance. A simultaneous fall in arterial blood pressure was also observed. Aminophylline, an adenosine antagonist, inhibited the haemodynamic as well as the metabolic responses evoked by the adenosine analogue. - In collagenase-isolated rat islets of Langerhans 765-21 inhibited glucose-induced insulin release in a dose-dependent manner (concentration range 10(-8) to 10(-5) M). In contrast to the data obtained on conscious dogs, 765-21 did not promote glucagon release from the pancreatic islets. Since stimulation of glucagon secretion was also not observed on decreasing the glucagon concentration in the incubation medium, the collagenase technique of isolation may be responsible for the insensitivity of the islets to glucagon-releasing stimuli. - The results are indicative of a specific inhibition of glucose-induced insulin release by 765-21. The data obtained in vivo additionally suggest a glucagon-releasing activity of the adenosine analogue investigated.
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PMID:[Effects of a long-acting adenosine analogue on insulin and glucagon release (author's transl)]. 700 70