Cells, adrenal

F (swollen adrenal cells with foamy cytoplasm and eccentric nuclei)... 

Aldosterone synthesis inhibition. Nicotine, anabasine, and cotinine, in freshly isolated rat adrenal cells at concentrations up to 100 mM, did not inhibit stimulated... 

NT27 6 Skowronski, R. J., and D. Feldman. Inhibition of aldosterone synthesis in rat adrenal cells by nicotine and related NT286 constituents of tobacco smoke. Endocrinology 1994 134(5) 2171-2177. 

This mechanism provides an explanation for the striking observation that addition of, for example, cholera toxin to cultured, rat-adrenal cells,542 or ovarian cells,543 leads to stimulation of the synthesis of eorti-eosterone or progesterone, mediated by cyclic AMP. Further examples of this toxin s causing a biological response in a wide variety of... 

Electrodes next to an adrenal cell measure release of the hormone epinephrine. [Photo courtesy R. M. Wightman, University of North Caroiina ]... 

It may be that the short half life protein has been missed because of the electrophoresis methods used. For example, a 3 kDa protein has recently been detected in adrenal cells that can stimulate steroid production in isolated mitochondria [50]. 

Corticosteroid Release from Adrenal Cell Suspensions in vitro... 

There are many modifications of this method, based on incubation of small fragments of adrenal glands, or on the use of dispersed adrenal cells. Cells are incubated in a physiological buffer. The final solution is gassed with a mixture of 95% O2 and 5% CO2 for 10 min. As with similar methods - for example for pituitary cells or dispersed Leydig cells - there... 

Corticosterone is now conveniently determined by RIA or HPLC, and dispersed adrenal cells are incubated instead of adrenal tissue fragments. 

PURPOSE AND RATIONALE For all new compounds which have some structural similarity or relation to the corticoid scaffold. There are now many such test systems which measure the initial membrane binding to the ACTH receptor, and to define the initial steps of hormone-related activation. However the binding affinity does not necessarily imply biological activation e.g. of adrenal cortical cells. Therefore, such tests always need to be followed up by a in-vitro testing on adrenal glands or dispersed adrenal cells. 

Corticotropin (ACTH) receptors have been used as the test preparations for comparison of the binding affinities of adrenocorticotropin peptides using a cloned mouse adrenocorticotropin receptor expressed in a stably transfected HeLa cell line (Kapas et al. 1996). Such assays measure the initial membrane binding but not strictly the biological activation e.g. of adrenal cells or melanocytes. 

In contrast, N- and P/Q-type Ca2+ currents are suppressed by stimulation of D1 receptors (Surmeier et al., 1995 Zhang et al., 2002). Surprisingly, inhibition of both PKA and PP-1 impairs the development of this effect. This suggests that the D1 receptor-dependent activation of PKA stimulates a PP-1-dependent dephosphorylation of Ca2+ channels, presumably by retargeting PP-1 in close vicinity of Ca2+ channels (Surmeier et al., 1995). In adrenal cells, dopamine inhibits T-type Ca2+ channel by stimulating... 

Deviller P, Vallier P, Bata J, Saez JM (1984) Distribution and characterization of cAMP-dependent protein kinase isoenzymes in bovine adrenal cells. Mol Cell Endocrinol 35 21-30. 

ANP is a 28-amino-acid peptide first discovered by de Bold et al. (2). It is released from heart atrial myocytes in response to a local arterial wall stretch. ANP acts on outer adrenal cells to decrease aldosterone production and blood pressure, increase salt and water excretion, and transudate plasma water to the interstitium (3). 

There have been frequent difficulties relating physiological effects to cyclic AMP levels. For example, adenosine inhibits the effect of noradrenaline on cyclic AMP accumulation in rat fat cells but does not interfere with the lipolytic effect of the catecholamine [58]. Both ACTH and its o-nitrophenyl sulphenyl derivative stimulate corticosterone synthesis in isolated rat adrenal cells to the same maximal rate, but the analogue has a 30- to 100-fold smaller effect than ACTH on cyclic AMP accumulation [60]. 

The effect of C2 toxin on release of granular mediators such as norepinephrine (Matter efal., 1989) and histamine (Bottinger efai, 1987) has been examined, but there is no clear picture that emerges from this work. Studies published to date indicate that the toxin does not have any effect on basal release. However, there may be effects on stimulated release, but the nature and even the direction of effect hinges on experimental conditions. In contrast to granular mediators, the basal release of at least one non-granular mediator is affected by toxin. The constitutive release of steroids in Y-1 adrenal cells was markedly stimulated by C2 toxin (Considine et a/., 1992). 

ACTH has been measured by bioassay, receptor assay, or immunoassay. Most bioassays are based on the effects of ACTH on adrenocortical cells (e.g, the stimulation of steroidogenesis or depletion of ascorbic acid). Responses are usually observed in the adrenal glands of hypophysec-tomized animals in situ or in isolated adrenal cells in vivo. In genera these bio assays are expensive and difficult to perform and are Hmited to research laboratories. Receptor assays use solubilized binding proteins obtained from normal or neoplastic adrenocortical ceUs. Only biologically active ACTH is measured, and a 10-pg/mL detection limit has been reported in unextracted plasma. These assays have limited application in the clinical laboratory partly because of the complexity and lability of receptor preparations. 

Since the effect of TSH on TPMP+ uptake precedes the effect of the hormone on adenylate cyclase activity,1 7 the possibility exists that a primary mode of action of each of these effectors is to alter electrochemical ion gradients across the cell membrane. This concept is attractive in that it would serve to explain certain other findings. Thus, hCG causes changes in adrenal cell ion transport which not only precede adenylate cyclase stimulation, but occur at concentrations of the effector which have minimal effects on cyclase activity 1 9 cholera toxin and its B protein induce alterations in the permeability of liposomes reconstituted with "receptor" ganglioside in the absence of adenylate cyclase.50 51... 

Primary adrenal cells from multiple species have also been used predominantly for investigative studies into normal signaling and function, although some toxicity studies have been reported [56-58]. This permits species-specific testing and interspecies comparisons [56, 59], We have characterized rat primary... 

EC50, concentrations that inhibits 50% of ACTH-stimulated cortisol secretion following a 60 min exposure in vitro LC50, concentrations that kills 50% of the adrenal cells following a 60 min exposure in vitro. 

---