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Results for “Chromaffin System”

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At least 19 recordsLinked to original sources
PubMed1989

Mitotic cell division in the extraadrenal chromaffin system of various species.

Mitotic activity often has been reported in embryonic and fetal sympathetic neuroblasts, principal sympathoblasts, and primitive sympathetic cells in various species at different stages of development. Postnatal adrenal medullary cells also are known to undergo mitosis, but such dividing capabilities rarely have been observed in the true postnatal extraadrenal chromaffin system. Although few in number, this work nevertheless has clearly identified such cells in varying stages of the mitotic cycle in the young dog, Syrian hamster, mouse, rabbit, and rat. The dividing cells were noted in paraaortic chromaffin organs, paraganglia, and within the inferior mesenteric ganglion as well. They displayed the morphological character usually associated with their adrenal medullary catecholaminergic counterparts, including numerous dense-cored vesicles known to be the harbingers of catecholamines and various peptides. Nerve endings were not noticed upon the mitotic cells. The phenomenon of dividing extraadrenal chromaffin cells augments existing data and perhaps suggests that these cells are more endocrine than neural in type and subservient to the adrenal medulla in its classic endocrine function.

Animals↗
PubMed1979

On the chromaffin system of the African lungfish, Protopterus aethiopicus.

The distribution of chromaffin tissue was studied in the African lungfish using Falck-Hillarp fluorescent histochemistry together with quantitative analysis of catecholamines in plasma and tissue extracts. Intensely fluorescent cells form chromaffin tissue in the wall of the atrium, the wall of the most anterior part of the left cardinal vein and the walls of the segmentally arranged intercostal arteries. The arrangement thus appears to be a combination of the situations in cyclostomes, elasmobranchs and teleosts. Adrenaline is present in larger quantities than noradrenaline in the intercostal arteries and the cardinal vein, while noradrenaline dominates in the atrium. During "stress" induced by physical disturbance of the animals, a strong increase in especially the noradrenaline concentration of the plasma was detected.

Animals↗
PubMed1991

Catecholamine release from bovine adrenal chromaffin cells during anoxia or metabolic inhibition.

A significant release of catecholamines within the heart has been observed during myocardial ischemia. Because this can be markedly inhibited by amine-uptake-blocking agents, it has been suggested that its mechanism is a carrier-mediated efflux from neurons, which is not operative under normal conditions. The present work examined this release process in chromaffin cells isolated from the bovine adrenal medulla, a model system for studying the sympathetic nervous system. Chromaffin cells in primary culture retained normal secretory responses for up to 7 days. Conditions designed to mimic ischemia, that is, anoxia or metabolic inhibition, resulted in a significant release of catecholamines. This release was shown to be independent of extracellular calcium but, in contrast to the release observed in ischemic hearts, was not inhibited by amine-uptake blockers. Electrophoresis with immunoblotting demonstrated that significant levels of the chromaffin granule protein, chromogranin A, were released during metabolic inhibition, indicative of an exocytotic mechanism. However, there was no release of the cytosolic protein, lactate dehydrogenase, indicating that there was no concomitant breakdown of the cell membrane. These results provide evidence for an exocytotic release of catecholamines mediated by the direct action of conditions of metabolic inhibition.

Adrenal Medulla↗
PubMed1985

Glucocorticoid receptors and regulation of phenylethanolamine-N-methyltransferase activity in cultured chromaffin cells.

Glucocorticoids are known to regulate the enzyme phenylethanolamine-N-methyltransferase (PNMT) in the adrenal medulla of the rat and are thereby thought to control the synthesis of epinephrine. We have examined the details of this relationship in a simplified system, chromaffin cell primary cultures derived from bovine adrenal medulla. Cultured chromaffin cells were found to have a cytosolic, high affinity, saturable glucocorticoid-binding protein with the steroid specificity of a classical glucocorticoid receptor and a Kd of approximately 1 nM. Treatment of cultured cells with dexamethasone or hydrocortisone at any time up to 21 days in culture increased PNMT activity in the soluble fraction of the cell. The concentration of hormone required to produce a half-maximal response was 10 nM dexamethasone when cells were cultured in the presence of 5% fetal calf serum, or 1 nM in a defined serum-free medium. These dose-response relationships are consistent with mediation of this effect by the glucocorticoid receptor. Unexpectedly, however, the glucocorticoid-induced increment in PNMT activity was not inhibited by cycloheximide at concentrations up to 50 microM, and an acceleration of protein synthesis by insulin treatment did not augment the glucocorticoid effect on PNMT. Treatment of the cells with dexamethasone (100 microM) prevented the decline in the epinephrine-to-norepinephrine ratio seen over time in culture, an effect consistent with increased PNMT activity. However, there was no effect of dexamethasone on the ability of the cells to secrete catecholamines in response to stimulation with high KCl or 30 microM nicotine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Identification of chromaffin granule-binding proteins. Relationship of the chromobindins to calelectrin, synhibin, and the tyrosine kinase substrates p35 and p36.

At least 23 soluble proteins (chromobindins) bind to chromaffin granule membranes in the presence of Ca2+. In order to further the identification of the chromobindins and to determine the roles they may play in exocytosis or other aspects of chromaffin cell biology, several of these proteins were compared to other known membrane-binding proteins. Chromobindin 4 was identified as a 32-kDa protein called calelectrin or endonexin. Immunologically related proteins were detected in bovine brain and human platelets. Chromobindin 20 was identified as a 67-kDa variant of calelectrin and was found to have the activities of the synexin inhibitory protein, synhibin. Chromobindin 8 was identified as p36, a substrate for the tyrosine-specific kinase, pp60v-src. Chromobindin 8 was also demonstrated to undergo phosphorylation predominantly on alkali-sensitive sites during stimulation of the chromaffin cell with 20 microM nicotine. Chromobindin 6 was identified as p35, a substrate for the tyrosine kinase activity associated with the epidermal growth factor receptor. Chromobindin 9, which is known to be a substrate for protein kinase C (Ca2+/phospholipid-dependent enzyme), was found to be immunologically related to p35 and may be a precursor of chromobindin 6. The identification of these proteins from the chromaffin system may be useful in the characterization of similar, complex groups of membrane-binding proteins that have been observed in other systems.

Amino Acids↗
PubMed1985

Retroperitoneal paraganglia and the peripheral autonomic nervous system in the human fetus.

By means of the AChE in toto staining method retroperitoneal paraganglia and the peripheral autonomic nervous system in human fetuses have been investigated. Many small retroperitoneal paraganglia are present near the sympathetic trunks close to the sympathetic trunk ganglia. In the thoracic region small paraganglia are present in the intercostal spaces. Small splanchnic nerves entering small paraganglia have been described. In the lower sacral region no paraganglia are present. The major splanchnic nerve arises at various levels from the sympathetic trunks as well as many smaller thoracic splanchnic nerves. Intermediate ganglia are present in the major splanchnic nerve, the smaller splanchnic nerves and the communicating rami. In the sympathetic trunks many ganglia are fused. In the human fetus there exists a large variability in number and diameter of the communicating rami. Interconnecting bundles of nerve fibers between the left and right sympathetic trunks are present at all levels, but most numerous at the sacral level.

Autonomic Nervous System↗
PubMedDate not supplied

[Adrenal medullitis in cases of human rabies].

The adrenal glands and the central nervous system were studied from five human cases of rabies who died three to six days after first rings of clinical manifestations were seen. In all cases there were Negri bodies in the cytoplasm of neurons of the central nervous system and mononuclear inflammatory cells around blood vessels, more intense in the cases with longer survival. Only the adrenal medulla showed diffuse and intense mononuclear exudate associated with pheocromocytes alterations in 60% of patients. Eosinophilic bodies were found in the cytoplasm of pheochromocytes and in the interstitial space. These bodies may be similar to Negri bodies but their true nature it is not known. The pathogenesis of adrenal medullitis in rabies may be related to embryological and metabolical relationships of the chromaffin system and the nervous system.

Adrenal Gland Diseases↗
PubMed1977

Monoamine-storing cells in the avian aortic wall.

Using the Falck-Hillarp method, monoamine-storing cells were demonstrated in the avian thoracic aorta just above the openings of the ductus arteriosus. By electron microscopy, numerous dense-cored vesicles, 90-220 nm in diameter, were seen in the cytoplasm. The electron opacity of these dense-cored vesicles was reduced when reserpine (5 mg/kg) was administered. These monoamine-storing cells formed typical synapses with the Schwann cell-enclosed nerve terminals. The monoamine-storing cells first appeared in the aortic wall at 9 days in ovo but it remained obscure whether they originated from the neuroectoderm.

Animals↗