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1.
Arch Biochem Biophys ; 424(1): 23-32, 2004 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-15019833

RESUMO

Adrenal chromaffin cells secrete catecholamines in response to cholinergic receptor activation by acetylcholine (ACh). Characteristics of Ca(2+) transients induced by activation of nicotinic (nAChRs) and muscarinic (mAChRs) receptors were analyzed using Fura-2 fluorescent measurements on rat chromaffin cells. We first found two populations of chromaffin cells, which differently responded on AChR stimulation. In the first group (n-cells), consecutive ACh applications evoked persistent Ca(2+) transients, whereas desensitizing transients were observed in the other group (m-cells). The AChR agonists and antagonists precisely imitated or abolished the ACh action on n- and m-type cells, respectively. Cytochemical staining showed that n-cells contained adrenaline, whereas m-cells-noradrenaline. Thus, for the first time we found that nAChRs and mAChRs are differentially expressed in adrenergic and noradrenergic chromaffin cells, respectively. Our data suppose that chromaffin cells can be differentially regulated by incoming ACh signals and in such way release different substances-adrenaline and noradrenaline.


Assuntos
Acetilcolina/farmacologia , Sinalização do Cálcio/fisiologia , Células Cromafins/fisiologia , Receptores Muscarínicos/fisiologia , Receptores Nicotínicos/fisiologia , Medula Suprarrenal/citologia , Animais , Atropina/farmacologia , Cálcio/química , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Agonistas Colinérgicos/farmacologia , Antagonistas Colinérgicos/farmacologia , Células Cromafins/química , Células Cromafins/efeitos dos fármacos , Células Cromafins/metabolismo , Citofotometria/métodos , Epinefrina/metabolismo , Histocitoquímica/métodos , Muscarina/farmacologia , Nicotina/farmacologia , Norepinefrina/metabolismo , Ratos , Receptores Muscarínicos/metabolismo , Receptores Nicotínicos/metabolismo , Tubocurarina/farmacologia
2.
Gen Comp Endocrinol ; 121(3): 261-77, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11254368

RESUMO

It has been previously shown that the neuron-like chromaffin cells from the bovine adrenal medulla are heterogeneous. Among other differences, the cells also differed in secretory vesicles represented in their cytoplasm. The present study investigates the types of secretory vesicles in bovine chromaffin cells by electron microscopy. Morphometric analysis revealed five types of electron-dense secretory vesicles in chromaffin cells. These were as follows: elementary large catecholamine-storing chromaffin granules of rounded shape, large dense core vesicles of ovoid and rod-like shapes, small dense core vesicles as well as ribosome-coated vesicles of intermediate density. Among the electron-lucent vesicles there were small synaptic-like microvesicles, endocytotic clathrin-coated vesicles, growth cone vesicles, and emptied large light core vesicles. The structural and functional backgrounds of different types of secretory vesicles are described, focusing on their formation and potential role.


Assuntos
Medula Suprarrenal/ultraestrutura , Grânulos Cromafim/ultraestrutura , Sistema Cromafim/ultraestrutura , Microscopia Eletrônica , Vesículas Secretórias/ultraestrutura , Animais , Bovinos , Vesículas Revestidas por Clatrina/ultraestrutura , Endocitose , Exocitose , Ribossomos/ultraestrutura , Sinapses/ultraestrutura
3.
Neuroscience ; 96(3): 639-49, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10717445

RESUMO

The ultrastructural organization on the fourth day of culture of chromaffin cells isolated from the bovine adrenal medulla was characterized based on electron microscopic and morphological analysis. We established that medullary chromaffin cells could be divided into four morphologically different subtypes. Most cells (49.1% of those examined) had a dense cytoplasm and fine dense granules. Cells with dense cytoplasm and large granules represented a second type of chromaffin cell (21.1%). Cells of the third type had a light cytoplasm, granules with a light halo and a well-developed Golgi apparatus (26.3%). The fourth type of chromaffin cell was characterized by moderately dense cytoplasm with well-expressed varicose rough endoplasmic reticulum (about 3.5%). Among concomitant cell types, cortical adrenal cells from the zona fasciculata and zona glomerulosa, epithelial cells, fibroblasts, lymphocytes, brown lipoblasts and glial Schwann cells were present. Morphological analysis implies that cells with dense cytoplasm and fine granules and those with light cytoplasm and haloed granules (75.4% in total) are adrenaline-containing cells, whereas the cells with dense cytoplasm and large granules (26.3%) contain noradrenaline. Cells with moderately dense cytoplasm and varicose reticulum share common morphological properties with classical glandular cells and, by their properties, were closer to noradrenaline-containing cells. It is concluded that chromaffin cells, which are the main cell type among cultured cells from adult bovine adrenal medulla, are morphologically quite heterogeneous. Other cell types of different nature may also be present in the culture and can locally influence the properties of the investigated medullary chromaffin cells used in electrophysiological experiments.


Assuntos
Medula Suprarrenal/citologia , Células Cromafins/ultraestrutura , Tecido Adiposo Marrom/citologia , Córtex Suprarrenal/citologia , Animais , Vasos Sanguíneos/citologia , Bovinos , Células Cultivadas , Citoplasma/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , Fibroblastos/ultraestrutura , Linfócitos/ultraestrutura , Microscopia Eletrônica , Neuroglia/ultraestrutura
4.
Comp Biochem Physiol Comp Physiol ; 108(2-3): 195-212, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-7914854

RESUMO

Using a variety of colloidal gold-labelled lectins with different sugar specificities, the structure and topography of carbohydrate determinants of the surface membrane of in vitro cultured glial and nerve cells of the snail Helix pomatia have been electron cytochemically studied. Heterogeneity of carbohydrate pools among different types of glial cells and between glial and nerve cells was established. It was found that satellite glial cells having the ultrastructural signs of cells with high metabolic level (type II cells) selectively bind GNA which is specific to terminal alpha-D-mannose residues and do not bind other mannose-specific lectins, Con A and LCA. GNA determinants are absent in satellite type I glial cells, fibrous glial cells, microglia and neurons. It has been found that glial cells (satellite type I and II glial cells, filamentous glial cells and microglial cells) do not bind PVA and LABA. LTA did not bind to any glial cells and binds weakly to neurons. Con A and WGA determinants which are abundant on the neurons are completely absent on satellite type II glial cells but present on satellite type I glial cells and filamentous glial cells. Microglial cells contain Con A and LCA determinants and the density of PNA determinants on these cells is the highest compared to other types of glial cells or neurons. It is concluded that some lectin determinants (for RCA-1, PNA, LPA) are present on all types of glial cells, while another determinant (GNA) is specific for a definite type of glial cells and can serve as a marker of these cells. The role of specific carbohydrate determinants in the functioning of a neuron-glial complex is discussed.


Assuntos
Carboidratos/química , Caracois Helix/fisiologia , Neuroglia/química , Animais , Sequência de Carboidratos , Células Cultivadas , Coloide de Ouro , Histocitoquímica , Lectinas , Microscopia Eletrônica , Dados de Sequência Molecular , Neuroglia/ultraestrutura , Neurônios/química , Neurônios/ultraestrutura
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