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M J Bastie

Publications and source records attributed to M J Bastie.

18 recordsLinked to original sources
PubMed1996

Loss of differences in mesangial cell phenotype between diabetic and normal rats: role of culture passages.

In mesangial cells (MC) isolated from streptozotocin (STZ)-induced diabetic rat kidneys, sensitivity to bradykinin (BK) for the induction of cell division and collagen synthesis, was found to be lower than in normal MC. Nevertheless, decreased activities could be reverted in vitro by insulin, at non-proliferative concentration (Girolami et al (1995), Can J Physiol Pharmacol 73, 848-853). The aim of the present study was to determine whether differences in the properties of diabetic MC could be ascribed to the diabetic state per se, and/or to experimental conditions, ie culture replating. Through successive cell replating, normal and diabetic types of MC were compared in terms of proliferation, contraction, free calcium concentration in response to KCl depolarization, and in relation to the expression of two cytoskeleton proteins specific to muscle cells, myosin and dystrophin. Studies of proliferation, contraction and free calcium concentration consistently showed that passage 5 was a limit beyond which differences between the two MC types were very small and sometimes non-significant. We found that the mean maximum contraction (MMC) and especially the proportion of contractile cells (PCC) among diabetic cells was lower than in normal MC. In addition, loss in proliferation activity and in [Ca2+]i concentrations were also found to occur during these five early passages. Dystrophin, a new marker of contractile phenotype recently described in smooth muscle cell (Leis et al (1994) Cell Biol Toxicol 10, 305), was first localized in MC and was compared with myosin also expressed in MC. However, during the course of cell replating and/or with the diabetic state, no visible quantitative changes were detected in the expression of the two contractile proteins. We conclude that cultured mesangial cells undergo phenotype modulations, as observed in other cells, in particular smooth muscle cells and consequently, comparative studies between normal and diabetic MC should not be carried out after the 5th passage.

Animals↗
PubMed1995

Different implications of Ca2+i and and Ca2+e in CCK/gastrin-induced amylase secretion in AR4-2J cells.

The importance of Ca2+ in the regulation of secretion is well-known. However, recent experiments suggest that a rise in intracellular Ca2+ (Ca2+i) does not necessarily trigger secretion in pancreatic acinar cells. In AR4-2J cells the role of the Ca2+ mobilization induced by cholecystokinin/gastrin (CCK/G), which is dependent of the intracellular calcium store and the calcium influx operating through voltage-dependent calcium channels, has never been directly demonstrated. Therefore, we attempted to determine whether Ca2+i and/or extracellular Ca2+ (Ca2+e) mobilized by CCK/G plays a role in the amylase secretion of these cells. We measured the [Ca2+]i by spectrofluorometry and amylase release in different experimental procedures modulating the two pools of calcium. Ionomycin increased both [Ca2+]i and amylase related. In Ca(2+)-depleted cells or in the presence of thapsigargin the transient rise in Ca2+i and the amylase secretion induced by CCK/G were suppressed. A 50 mM K+ solution or Bay K 8644, which activated the Ca2+ influx, did not induce any variation of the basal amylase secretion. Moreover, amylase secretion induced by CCK/G did not change significantly in Ca(2+)-free medium or in the presence of nifedipine. These results indicate that in AR4-2J cells, amylase secretion is dependent of the large increase in Ca2+i induced by CCK/G and independent of the Ca2+ influx through voltage-dependent calcium channels dihydropyridine sensitive.

Amylases↗
PubMed1993

Evidence for existence of two distinct bradykinin receptors on rat mesangial cells.

We investigated the possible presence of bradykinin (BK) B1 receptor on rat mesangial cells (MC) by binding studies and by the effect of the B1 agonist des-Arg9-BK on intracellular calcium concentration ([Ca2+]i) and DNA synthesis in comparison with the effects of BK. Binding studies demonstrated specific, saturable binding for des-Arg9-[3H]BK inhibited by B1 but not by B2 antagonists. Scatchard analysis revealed a single class of B1 binding site with a maximum density of 15 fmol/mg protein and an affinity of 8.7 +/- 2.4 nM. Saturation and competition studies of 125I-[Tyr0]BK demonstrated the presence of two classes of B2 binding sites [dissociation constant (Kd) = 0.1 and 4 nM, respectively]. On fura-2-loaded adherent MC, both des-Arg9-BK and BK induced a biphasic increase (a transient enhancement followed by a sustained phase) in [Ca2+]i, both in primary culture and in cloned MC. Both the transient and sustained phases of [Ca2+]i induced by des-Arg9-BK were dose dependent, whereas BK induced a transient dose-dependent rise in [Ca2+]i, but the sustained phase remained constant. The increases in [Ca2+]i induced by des-Arg9-BK and BK were specifically abolished by B1 and B2 receptor antagonists, respectively, and showed homologous but not heterologous desensitization. Des-Arg9-BK and BK induced a significant proliferation (tested by cell counting and [3H]thymidine incorporation) of quiescent MC. Furthermore, the effects of des-Arg9-BK and BK were additive on Ca2+ mobilization but not on mitogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Na+/H+ exchange in AR4-2J cells: stimulation by growth factors and pancreatic secretagogues.

To study the relationships between activation of the Na+/H+ antiporter and gastrointestinal cell proliferation, we characterized this antiporter in a pancreatic cell line (AR4-2J). In the present study, the effects of mitogenic and non-mitogenic agents and of Na+/H+ exchange blocking agents on DNA synthesis are reported. Dialyzed fetal calf serum (FCS) (0-10%) increased amiloride-sensitive 22Na+ uptake in a concentration-dependent manner. There was a linear relationship between the increase in 22Na uptake and cell number when FCS was added in the 2-10% concentration range. Amiloride and analogs inhibited 3H-thymidine incorporation in the same concentration range as that with which they inhibited the Na+/H+ exchange. IC50 values were 1 microM for 5-(N-ethy-N-isopropyl)-amiloride (EIPA), 10 microM for 5-(N,N-dimethyl)-amiloride (DMA) and 0.1 mM for amiloride, respectively, indicating that activation of the Na+/H+ antiporter is necessary to initiate cell proliferation in AR4-2J cells. Maximal CCK9-induced 22Na uptake was 3.65 times the basal rate and was obtained at 0.1 nM. Maximal 22Na uptake triggered by unsulfated gastrin 17 was 2.51 times the basal rate and was obtained at 0.1 nM. The EC50s of CCK9 and gastrin in stimulating the 22Na uptake were similar at 1 pM. Maximal carbamylcholine-induced stimulation was observed at 0.1 mM and was 2.37 times greater than the basal rate. EC50 was 1 microM. In AR4-2J cells, the activity of the Na+/H+ exchanger seems to be directly involved in the control of cell proliferation. However, stimulation of this exchanger by stimulating factors that are not growth factors suggests that intracytoplasmic alkalinization could regulate other important metabolic processes which, as yet, are unknown.

Amiloride↗
PubMed1988

Distinct activation of Na+-H+ exchange by gastrin and CCK peptide in acini from guinea pig.

The effect of cholecystokinin (CCK)-gastrin family peptides (caerulein, unsulfated gastrin-17, and pentagastrin) and secretin in activating amiloride-sensitive 22Na uptake were investigated in guinea pig pancreatic acini. Secretin had no effect, but CCK-gastrin peptides stimulated the amiloride-sensitive 22Na uptake. The effect of caerulein was inhibited by dibutyryl guanosine 3',5'-cyclic monophosphate (cGMP) and asperlicin, indicating that activation of the Na+-H+ antiport caused by caerulein is mediated by CCK receptors. The effect of gastrin was dibutyryl cGMP and asperlicin insensitive, whereas the effect of pentagastrin was inhibited by the CCK antagonists but with a low affinity, indicating that the effect of gastrin and that of pentagastrin was CCK receptor independent. The calcium ionophore A23187 caused an increase in amiloride-sensitive 22Na uptake. However, the effect of caerulein, which increased internal calcium concentration, was not modified after depletion of intracellular calcium, and that of CCK-gastrin family peptides was not dependent on external calcium concentration. Activation of amiloride-sensitive 22Na uptake was also induced by 12-O-tetradecanoylphorbol 13-acetate and 1-oleoyl-2-acetyl-glycerol. Activation of protein kinase c may be involved in the mechanism of caerulein or gastrin in activating the Na+-H+ exchange.

Amiloride↗
PubMed1985

The amiloride sensitive Na+/H+ antiport in guinea pig pancreatic acini. Characterization and stimulation by caerulein.

Amiloride and analogs decrease the initial rate of 22Na+ uptake by dispersed acini from guinea pig pancreas in a dose-dependent manner. The initial rate of amiloride-sensitive 22Na+ uptake depends on external Na+ and H+ concentrations and on internal pH. These results provide evidence for the existence of a Na+/H+ antiport in pancreatic acinar cells. Caerulein, a cholecystokinin analog, stimulates the activity of the Na+/H+ antiport.

Amiloride↗
PubMed1985

Comparative study of histological and kinetic variations of the digestive mucosa and pancreatic parenchyma after hypophysectomy in the rat. Light and electron microscopic study.

Variations of the pancreatic parenchyma, the gastric mucosa and the intestinal mucosa were studied in adult male Wistar rats on day 8 and 15 after hypophysectomy. All results were compared with those obtained in pair-fed control rats. Hypophysectomy affected small intestine as well as gastric mucosa. Hypotrophy was observed on day 8 as most of the morphological parameters reached the maximal decrease. By contrast, hypoplasy occurred on day 15, when the labeling index (LI) decreased significantly. In the intestine, however, a decrease of the LI was observed only for the upper proliferative cells of the crypts. In the gastric mucosa, the LI was reduced only in the proliferative zone containing progenitor cells (isthmic region). Consequently, the cell differentiation is not similarly affected on all levels of the digestive tract.

Animals↗
PubMed1984

[Cytologic demonstration of immunoreactivity characteristic of adenopituitary peptides in the digestive epithelium of the rat and man].

Using immunoperoxidase techniques, the possible localization of pituitary regulatory peptides in fundic, antral and duodenal mucosae was investigated in both rat and man. All results obtained were similar in the two species. No glycopeptide (FSH, LH, TSH) was detected in the digestive tract. With different antisera directed against beta-lipotropin, alpha-MSH, beta-MSH, endorphins, ACTH 1-24, ACTH 17-39, a positive reaction was only obtained in the antral mucosae with an antiserum specific for the synthetic fragment 17-39 of ACTH. However neither the common precursor, proopiomelanocortin, nor the complete sequence of ACTH seem to be present in endocrine cells of the digestive tract. On the other hand, three antisera, directed against human growth hormone (GH), visualized numerous endocrine cells scattered in the glandular epithelium of the fundic and antral mucosae. Most cells were identified as ECL type in the gastric mucosae. Others are probably of the gastrin cell type in the antral mucosa, since these cells could be visualized on adjacent sections either with the antiserum against GH, or with a specific antiserum for gastrin.

Adrenocorticotropic Hormone↗
PubMed1982

Histological variations of the duodenal mucosa in chronic human pancreatitis.

From 16 volunteers with chronic pancreatitis and 36 healthy subjects duodenal biopsies were taken 15--20 cm beyond the papilla of Vater. Several morphometric parameters were calculated. The main results show: a significant decrease of villous area and height but not of the number of intestinal villi; a significant increase of Paneth cells; and a slight decrease in the number of glandular mitoses. This study suggests in man, a possible relationship between exocrine pancreatic secretion and the intestinal mucosa and a trophic action of pancreatic juice on the proliferation and the differentiation of the intestinal mucosa.

Biopsy↗
PubMed1981

Long term effects of H2-receptor antagonists (cimetidine and ranitidine) on the human gastric and duodenal mucosa.

Cytological effects of two H2-receptor antagonists on the gastric and duodenal mucosa were studied during therapy of active duodenal ulcer (D.U.) in man. After endoscopic diagnosis (day 0), subjects were treated with cimetidine or ranitidine and re-examined on day 30. Only subjects with healed D.U. on day 30 were retained in this study. Gastric, pyloric and duodenal endoscopic biopsies were taken and treated for further morphometrical analysis both by light and electron microscopy. The use of the immunoperoxidase technique allowed evaluation of G and D cell populations. Kinetic parameters in proliferative zones were measured after in vitro incubation of biopsies with 3H-thymidine. No differences could be seen between the two H2-receptor antagonists. Increase of tubulovesicles and decrease of canaliculi in parietal cells are closely related to the inhibitory effect of these drugs on acid secretion. However secretory capacities of parietal cells are preserved since the whole membrane (tubulovesicle + canaliculi surface) remained constant. The collapsed aspect of the tubulovesicles on day 30 and the presence of connections between the tubulovesicle membrane, with both vesicle and canaliculi membrane, could support the theory of osmotic membrane expansion during parietal cell acid secretion. H2-receptor antagonists have been shown to be trophic in duodenal mucosa: both villi and microvilli area are increased. Confirming these findings, the proliferative compartment in the intestinal crypts was shown to be enlarged. No variation of G cell number could be seen in the antral mucosa; clear intracytoplasmic granules were increased in D.U. on day 0 but were not further modified on day 30. Somatostatin labelling index decreased. These last findings associated with the lack of G cell variations, suggest the presence of a possible paracrine modulation in the gastric and duodenal mucosa.

Biopsy↗
PubMed1979

A cyto-physiological study of the G-cell secretory cycle in the antrum mucosa of the hamster and of the rat.

The secretory cycle of the antral G cell in the golden hamster and in the Wistar rat has been investigated, using classical techniques of optical and electron microscopy associated with special methods (such as goniometry, densitometry, immunohistology, morphometry) and with radioimmunoassay for gastrin. This paper confirms the secretory cycle of the G cell after refeeding. It clarifies the nature of granule polymorphism and suggests a particular mechanism of emiocytosis with sequential granule fusion. Furthermore, our investigations show some dissociations between the G cell, the parietal cycle, and the seric immunoreactive gastrin in the late phase of the secretory cycle (2 to 6 h after refeeding).

Animals↗
PubMed1977

Effects of catecholamines and their inhibitors on the isolated canine pancreas. I. Noradrenaline and isoprenaline.

alpha Adrenergic agonist (noradrenaline, 2, 20, and 200 mug) and antagonist (phenoxybenzamine, 15 mg), and beta adrenergic agonist (isoproterenol, 2, 20, and 200 mug), and antagonist (propranolol, 6 mg), were tested on isolated perfused canine pancreas under basal conditions, and under stimulation by a background of secretin (0.5 clinical unit per hr), or of caerulein (600 to 1200 ng per hr). Noradrenaline induced a strong vasoconstriction (inhibited by phenoxybenzamine), followed by a moderate vasodilation (possibly mechanical). Noradrenaline did not stimulate a resting pancreas and inhibited a pancreas from secreting in response to secretin or caerulein. After phenoxybenzamine, in the absence of vasoconstriction, this latter effect was reversed into a dose-dependent stimulation of hydrelatic secretion, suggesting that noradrenaline had a direct action on the secretory cell. There was no stimulation of protein and no acinar degranulation. Propranolol and atropine did not modify the effectiveness of noradrenaline. Isoprenaline had a weak vasodilatory effect but no effect on the secretion. Adrenergic blocking agents did not alter the response to secretin or caerulein.

Animals↗
PubMed1977

Effects of catecholamines and their inhibitors on the isolated canine pancreas. II. Dopamine.

Dopaminergic agonists (dopamine, 2, 10, 50, and 250 mug; apomorphine, 1 mg; noradrenaline, 2, 20, and 200 mug), and inhibitors (haloperidol, 5 mg; pentamethonium, 500 mg; phenoxybenzamine, 15 mg, and atropine sulfate, 10 mg), were tested on isolated perfused canine pancreas; under basal conditions and under stimulation by a background of secretin (0.1, 0.5, and 10.0 clinical unit per hr), or of caerulein (1200 ng per hr). Low doses of dopamine induced a vasodilation inhibited by haloperidol Large doses induced a vasoconstriction, presumably by stimulation of alpha adrenergic receptors. Dopamine stimulated hydrelatic secretion. The calculated maximal response was about one-half that of secretin. This response was inhibited by haloperidol but not by atropine, pentamethonium, and phenoxybenzamine. No acinar degranulation was observed after stimulation by dopamine. The response to secretin was not altered by haloperidol. It was concluded that blood vessels and pancreatic tissue contain specific receptors to dopamine different from secretin receptors. Secretory response to noradrenaline after phenoxy benzamine was inhibited by haloperidol, suggesting that this effect was mediated by the stimulation of dopamine receptors of the cells. A hypothetical representation of the interrelation between dopamine, secretin, and noradrenaline is discussed.

Animals↗
PubMedDate not supplied

Interleukin-6 regulation of CCK/gastrin receptors and amylase secretion in a rat pancreatic acinar cell line (AR4-2J).

In necrotizing pancreatitis a high interleukin-6 (IL-6) serum level has been proposed as a prognostic criterium. However, literature does not report any information about the role of IL-6 in the function of pancreatic acinar cells. Cholecystokinin, gastrin binding, amylase release and intracellular calcium measurement were performed on a rat pancreatoma cell line, AR4-2J, which has been recognized as a useful tool for studies on the long-term regulation of pancreatic acinar cells. The addition of IL-6 (400 pM) for 48hrs to the AR4-2J cells induced no change in the binding affinities but there was a 2 fold increase in the binding capacity of cholecytokinin (CCKA R) and gastrin (CCKB R) receptors. Although IL-6 treatment did not change directly the secretory capacity and did not activate the intracellular calcium mobilization of AR4-2J, it indirectly increased the sensitivity of the cells to the stimulation of amylase release and the intracellular calcium mobilization by cholecystokinin and gastrin. It is most likely this effect was due to the IL-6-induced increase in the numbers of CCKA R and CCKB R. Therefore this report suggests that the cytokine IL-6 acts on the CCK regulation of pancreatic enzyme secretion.

Amylases↗