Am J Physiol Heart Circ Physiol
November 2002
The presence of a local renin-angiotensin system has been established in organs that serve as angiotensin targets. In this study, the expression of angiotensinogen mRNA and subcellular localization of renin, angiotensin-converting enzyme, and angiotensin II were investigated in bovine adrenal medullary cells in primary culture. By light microscopy, expression of angiotensinogen mRNA, immunoreactive renin, angiotensin-converting enzyme, and angiotensin II were readily detectable only in the chromaffin cells.
View Article and Find Full Text PDFThe study of secretory vesicle dynamics is a continuing challenge. Classically it was studied using biochemical techniques, such as subcellular fractionation and immunoprecipitation, combined with time-consuming electron microscopy studies. The recent development of confocal microscopy, giving in-focus optical section images throughout the thickness of a fluorescently labeled sample, allows scientists to study the key events in the secretory cycle at the level of light microscopy.
View Article and Find Full Text PDFRab3a, a small GTP-binding protein, is believed to mediate Ca2+-dependent exocytosis. Consistent with such a role was the previously reported specific association of Rab3a with synaptic vesicles in neurons and secretory granules in adrenal chromaffin cells. Secretory vesicles are believed to be the final point of Rab3a membrane association, as it was shown by several groups that Rab3a dissociates from the secretory vesicle membrane during stimulated exocytosis.
View Article and Find Full Text PDFTwo storage compartments in cultured noradrenergic neurons derived from the superior cervical ganglion from fetal pig have been defined using sucrose density gradient centrifugation and electron microscopy: (1) large dense-cored vesicles (LDV) contain noradrenaline and dopamine-beta-hydroxylase (DbetaH); (2) small electron-lucent vesicles contain acetylcholine and p38 and represent the noradrenergic small synaptic vesicles (SSV); no small dense-cored vesicles (SDV) could be detected. Our results demonstrate that internalized LDV membrane constituents are retrieved into early endosomes, as shown by the colocalization of retrieved DbetaH with the endosomal markers Rab5 and HRP in sucrose density gradients and on confocal microscopical images. Recycling of the SSV membranes via an endosomal intermediate is also confirmed in noradrenergic neurons.
View Article and Find Full Text PDFIn this study we have used primary cultures of porcine superior cervical ganglia as a model system to study exo-endocytosis in sympathetic neurons. Pure neuronal cultures with a defined noradrenergic phenotype can be obtained when antimitotics are included in the culture medium, and the high yield from prenatal piglets allows a biochemical approach in addition to morphological studies. Release of large dense-cored vesicles (LDCVs) was visualized by exposing stimulated neurons to anti-dopamine-beta-hydroxylase (D beta H) prior to fixation.
View Article and Find Full Text PDFBiochem Biophys Res Commun
December 1996
Although the presence of a local renin-angiotensin system has been established in a number of tissues, evidence for the existence and expression of the components of the renin-angiotensin system in peripheral adrenergic neurons is still missing. Here we provide the results showing the expression of angiotensinogen mRNA and localization of renin and angiotensin II in primary cultured fetal pig superior cervical ganglion neurons but not in non-neuronal cells by in situ hybridization with biotinylated oligodeoxynucleotide probe and immunocytochemical approaches. Our confocal laser scanning microscopical results confirm that angiotensinogen mRNA is expressed in the renin containing neurons.
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