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1.
W B Cornelissen A B de Laet A B Kroese D W Adriaensen P P van Bogaert D W Scheuermann J P Timmermans 《European journal of morphology》1999,37(4-5):241-249
Although autonomic gastrointestinal reflex movements, which occur in all mammalian species, have been described almost a century ago, little was known on the mechanisms underlying this behaviour. Recently, however, intrinsic primary afferent neurones, functioning as the first relay in the reflex arches embedded in the intestinal wall, have been identified in the guinea pig ileum. In guinea pig, such neurones display a Dogiel type II morphology and behave electrophysiologically as slow AHP neurones. In other gastrointestinal regions, in both guinea pig and rat, Dogiel type II cells are also encountered, but the strong correlation with slow AHP neuronal features seems less strict. In large mammals, a correlation of the cellular morphology with intracellular el ectrophysiological recordings has only been obtained in the pig small intestine. Surprisingly, in these experiments aberrant electrophysiological behaviour of Dogiel type II neurones is even more striking since the majority of these cells display electrophysiological features considered typical of S neurones. Furthermore, in those rare cases in which a slow afterhyperpolarization (AHP) could be recorded in porcine Dogiel type II cells, its amplitudes were negligible. This has led us to the conclusion that the differences in electrophysiological behaviour of neurones with comparable morphology in different species are most probably due to the modulating influence of the neurotransmitter substances present. This seems to be the most likely hypothesis in view of the considerable differences in neurotransmitter content of neurones with comparable functions throughout the species. 相似文献
2.
Summary In view of the presumed involvement of gap junctions in the coordination of metabolic activities, the influence of cAMP as a regulatory signal of cell metabolism on gap junctions of hepatocytes has been examined. Male rats received two intraperitoneal doses of 10 mg dibutyryl cAMP/100 g body weight with a time interval of 2.5 h and were decapitated 2.5 h later. After this 5-h interval, analysis of freeze-fracture replicas of fixed liver tissue revealed an increase in the mean (± SEM) gap-junctional membrane portion on the lateral hepatocyte membranes from 0.049 + 0.003 (n = 66) in controls to 0.061 ± 0.003 (n = 70) in treated rats, while the configuration of the connexons appeared unaltered. This effect could not be reinforced by prior administration of aminophylline: the relative gapjunctional area is similarly extended from 0.054 ± 0.003 (n = 126) in the control group to 0.065 ± 0.004 (n = 105) in the experimental animals. Probing for the time course of the junctional response, a group of rats was sacrificed 3 h after the onset of treatment. Already within this time, the gapjunctional area is augmented from 0.042 ± 0.004 (n = 63) in the concurrent controls to 0.069 ± 0.006 (n = 42) in the treated rats. These statistically significant increases in area may suggest a stimulating effect of cAMP on gap junctions of hepatocytes in vivo.This investigation was supported by grant No. 3.0059.81 (to D.W.S.) from the Fund for Medical Scientific Research (Belgium) 相似文献
3.
D. W. Scheuermann Ch. Stilman M. H. A. De Groodt-Lasseel 《Histochemistry and cell biology》1988,88(3-6):219-225
Summary To demonstrate the intracellular store of 5-hydroxytryptamine and dopamine in pulmonary neuroepithelial bodies of the neonatal rabbit after treatment with the corresponding amino-acid precursorsl-5-hydroxytryptophan orl-3,4-dihydroxyphenylalanine, formaldehyde-induced flourescence in combination with microspectrofluorimetric analysis has been used. Emission spectra and excitation spectra in an extended wavelength range from 240 to 460 nm, the displacement of excitation peaks after exposure to hydrochloric acid vapour, and calculation of peak ratio values 410/260, 380/320, 320/260 for phenylethylamine fluorophores and 385/315 for indolylethylamine fluorphores were performed. Thus, the presence of 5-hydroxytryptamine without occurrence of 5-hydroxytryptophan was demonstrated in pulmonary neuroepithelial bodies after administration of the corresponding biological precursor, while dopamine combined with 5-hydroxytryptamine were clearly revealed after administration ofl-3,4-dihydroxyphenylalanine. The rate of photodecomposition always corroborated these findings.Dedicated to Prefessor Dr. T.H. Schiebler on the occasion of his 65th birthdaySupported by grant nr. 3.0059.81 (to D.W.S.) from the Fund for Medical Scientific Research (Belgium) 相似文献
4.
The present scanning electron microscopical (SEM) study was initiated to visualize the surface topography of Auerbach's plexus in the ileum of the pig. After enzymatic digestion of the connective-tissue components of the tunica muscularis and the tunica serosa followed by glutaraldehyde fixation, HCl-hydrolysis and stripping off either the longitudinal or circular smooth muscle layer, the three-dimensional architecture and topographical features of the myenteric plexus can clearly be observed. In this way, ganglia, primary, secondary and tertiary strands, and single nerve fibres can be demonstrated. Individual nerve cells, which are incompletely covered by glial cells and by remnants of the basal lamina, can be recognized in the centre and periphery of the ganglia and adjacent to primary and secondary nerve strands. 相似文献
5.
J.-P. Timmermans D. Adriaensen D. W. Scheuermann A. Boros E. Fekete 《Histochemistry and cell biology》1994,101(5):365-374
Using immunocytochemistry, NADPH-diaphorase (NADPHd) histochemistry and electron microscopy, the appearance of nitrergic enteric neurons in different digestive tract regions of the embryonic, neonatal and adult quail was studied in whole mounts and sections. NADPHd was first expressed by embryonic day 4–5 in two distinct locations, namely the mesenchyme of the gizzard primordium and at the caeco-colonic junction. At embryonic day 6, nitrergic neurons had already begun to form a myenteric nerve network in the wall of the proventriculus, gizzard and proximal part of the large intestine and by embryonic day 9, a myenteric network was visualized along the entire digestive tract of the quail. At the level of the stomach, this network was confined to the area covered by the intermediate muscles. By embryonic day 12–13, the NADPHd-positive myenteric neurons in the wall of the distal parts of the blind-ending paired caeca also became organized into ganglia. From this developmental stage on, a submucous nitrergic nerve network, sandwiched between the lamina muscularis mucosae and the luminal side of the outer muscle layer, became prominent in the proventriculus and intestinal walls. In the adult quail, only a minority of the NADPHd-positive neurons stained for vasoactive intestinal polypeptide (VIP) along the intestine. VIP-immunoreactive (IR) cell bodies were frequent in the myenteric plexus but not in the submucous plexus, whereas there were considerable numbers of NADPHd-positive neurons in both these plexuses. Nitrergic fibres were also observed in the outer muscle layer, but were almost absent from the lamina muscularis mucosa and lamina propria, in contrast to the dense VIP-ergic innervation encircling the bases of the intestinal crypts. 相似文献
6.
J. -P. Timmermans M. Barbiers D. W. Scheuermann W. Stach D. Adriaensen M. H. A. De Groodt-Lasseel 《Cell and tissue research》1993,272(1):49-58
The small intestine of the pig has been investigated for its topographical distribution of enteric neurons projecting to the cranial mesenteric ganglion, by using Fast Blue or Fluorogold as a retrogradely transported neuronal tracer. Contrary to the situation in small laboratory animals such as rat and guinea-pig, the intestinofugally projecting neurons in the porcine small intestine were not restricted to the myenteric plexus, but were observed in greater numbers in ganglia of the outer submucous plexus. The inner submucous plexus was devoid of labelled neurons. Retrogradely labelled neurons were mostly found, either singly or in small aggregates, in ganglia located within a narrow border on either side of the mesenteric attachment. For both nerve networks, their number increased from duodenum to ileum. All the retrogradely labelled neurons exhibited a multidendritic uniaxonal appearance. Some of them displayed type-III morphology and stained for serotonin. This study indicates that, in the pig, not only the myenteric plexus but also one submucous nerve network is involved in the afferent component of intestino-sympathico-intestinal reflex pathways. The finding that some of the morphologically defined type-III neurons participate in these reflexes is in accord with the earlier proposal that type-III neurons are supposed to fulfill an interneuronal role, whether intra- or extramurally. 相似文献
7.
8.
In thin sections and in freeze-fracture replicas small and sparse gap junctions appear to be developed on the longitudinal plasma membrane of Protopterus cardiac cells near a macula or fascia adhaerens. By thin-section electron microscopy, they had septalaminar profiles with a length between 0.042 and 0.260 micron. In freeze-fracture images they appear on the P-fracture face as maculate particle aggregations with complementary pits on the E-fracture face. Particles with a central intercellular channel could be observed. The average center-to-center distance between neighbouring particles or pits is 10.05 +/- 1.87 nm (N = 2429). The diameter of the junctional maculae in replicas lies between 0.037 and 0.229 nm. The particle packing density increases in larger maculate aggregations, while particle-free areas emerge which could be related to the degradation or reformation of gap junctions Atypical configurations of gap junctions observed in the myocardium of lower vertebrates are rarely encountered in this primitive vertebrate. 相似文献
9.
Sarah Rouhana Charlotte Farah Jerome Roy Amanda Finan Glaucy Rodrigues de Araujo Patrice Bideaux Valérie Scheuermann Youakim Saliba Cyril Reboul Olivier Cazorla Franck Aimond Sylvain Richard Jérôme Thireau Nassim Fares 《生物化学与生物物理学报:疾病的分子基础》2019,1865(1):230-242
Heart failure with preserved ejection fraction (HFpEF) is a common clinical syndrome associated with high morbidity and mortality. Therapeutic options are limited due to a lack of knowledge of the pathology and its evolution. We investigated the cellular phenotype and Ca2+ handling in hearts recapitulating HFpEF criteria. HFpEF was induced in a portion of male Wistar rats four weeks after abdominal aortic banding. These animals had nearly normal ejection fraction and presented elevated blood pressure, lung congestion, concentric hypertrophy, increased LV mass, wall stiffness, impaired active relaxation and passive filling of the left ventricle, enlarged left atrium, and cardiomyocyte hypertrophy. Left ventricular cell contraction was stronger and the Ca2+ transient larger. Ca2+ cycling was modified with a RyR2 mediated Ca2+ leak from the sarcoplasmic reticulum and impaired Ca2+ extrusion through the Sodium/Calcium exchanger (NCX), which promoted an increase in diastolic Ca2+. The Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA2a) and NCX protein levels were unchanged. The phospholamban (PLN) to SERCA2a ratio was augmented in favor of an inhibitory effect on the SERCA2a activity. Conversely, PLN phosphorylation at the calmodulin-dependent kinase II (CaMKII)-specific site (PLN-Thr17), which promotes SERCA2A activity, was increased as well, suggesting an adaptive compensation of Ca2+ cycling. Altogether our findings show that cardiac remodeling in hearts with a HFpEF status differs from that known for heart failure with reduced ejection fraction. These data also underscore the interdependence between systolic and diastolic “adaptations” of Ca2+ cycling with complex compensative interactions between Ca2+ handling partner and regulatory proteins. 相似文献
10.
Ann M. G. L. De Mazière Dietrich W. Scheuermann Philip A. P. M. Aertgeerts 《The Journal of membrane biology》1987,97(2):107-115
Summary Particles and pits of freeze-fractured gap junctions are considered as complementary structures despite the frequent observations of more regular and closer spacings of pits, ascribed to plastic deformation of particle arrays. Recently, however, the noncomplementarity of pits and particles in Purkinje fibers has been reported. To ascertain the relationship between both structures, gap junctions from fixed, cryoprotected liver and myocardium were investigated using spacing and density measurements and complementary replicas.In hepatocyte gap junctions, the center-to-center distances (mean±sd) among pits, 9.57±1.49 nm, and particles, 9.70±1.77 nm, are not significantly different. Density determinations yielded a slightly higher value for the pits, (11,510±830)/m2, than for the particles, (11,230±950)/m2. In the myocardium, the spacing of the regularly arrayed pits, 9.55±1.33 nm barely exceeds the value of 9.44±1.62 nm for the particles, which show some clustering. However, the packing density for the pits, (10,090±740)/m2, appears a little higher than that of the particles (9,890±920)/m2. As density and spacing measurements provided no decisive answers, the positions of individual pits and particles of complementary junctional faces were recorded on transparent sheets and compared. In this fashion, a one-to-one correspondence between particles and pits could be established, while small discrepancies may be attributed to plastic deformation. Moreover, the collinearity of pits and particles may be suggested by the observation of a platinum grain in the center of many pits. 相似文献