Effects of corticoid agonists and antagonists on apical Na+ permeability of toad urinary bladder

1994 ◽  
Vol 266 (1) ◽  
pp. F108-F116 ◽  
Author(s):  
H. Garty ◽  
K. Peterson-Yantorno ◽  
C. Asher ◽  
M. M. Civian
Keyword(s):  
Urinary Bladder ◽  
Glucocorticoid Receptors ◽  
Membrane Vesicles ◽  
Receptor Occupancy ◽  
Toad Urinary Bladder ◽  
Type I ◽  
Type Ii ◽  
Plasma Membrane Vesicles ◽  
Mineralocorticoid Antagonist ◽  
Amphibian Urinary Bladder

Effects of RU-28362 (glucocorticoid agonist), RU-38486 (glucocorticoid antagonist), and RU-26752 (mineralocorticoid antagonist) on the apical Na+ permeability of toad bladder were measured and correlated with occupancies of cytosolic type I (mineralocorticoid) and type II (glucocorticoid) receptors. Effects of the above steroids were measured in whole bladders, plasma membrane vesicles, and RNA-injected Xenopus oocytes. RU-38486 was found to fully displace aldosterone from type II receptors without affecting type I occupancy. Under these conditions, RU-38486 inhibited approximately 35% of the effect of aldosterone measured in the whole tissue and isolated membranes. Unexpectedly, oocytes injected with RNA from tissue stimulated with aldosterone plus RU-38486 expressed channel activity that was much higher than the sum of activities induced by either steroid alone. RU-28362 and RU-26752 at concentrations sufficient to fully occupy both receptors had only partial agonistic and antagonistic effects, respectively. The results suggest that at least one-third of the natriferic action of aldosterone measured in the amphibian urinary bladder is mediated by the glucocorticoid receptor. However, some of the effects observed cannot be accounted for by a simple receptor occupancy-response scheme.

Ketamine, an N -methyl-d-aspartate Receptor Antagonist, Inhibits the Spinal Neuronal Responses to Distension of the Rat Urinary Bladder

2002 ◽  
Vol 96 (6) ◽  
pp. 1410-1419 ◽  
Author(s):  
Pablo J. Castroman ◽  
Timothy J. Ness
Keyword(s):  
Spinal Cord ◽  
Urinary Bladder ◽  
Spinal Dorsal Horn ◽  
Type I ◽  
Type Ii ◽  
Neuronal Responses ◽  
Spinal Dorsal ◽  
Aspartate Receptor ◽  
Dose Dependent ◽  
Intravenous Ketamine

Background The effect of ketamine as a treatment of visceral pain is not known. The current study investigated the effect of ketamine on spinal dorsal horn neurons excited by urinary bladder distension (UBD). The effect of other clinically available N-methyl-D-aspartate receptor antagonists on these responses was also studied. Methods Extracellular recordings of neurons located in the L6-S2 spinal dorsal horn of cervical spinal cord-transected, decerebrate female rats were obtained. Cutaneous receptive fields of neuronal units excited by UBD were characterized for responses to segmental noxious and nonnoxious stimuli. Nonsegmental noxious stimuli were also applied, and neurons were classified as type I (inhibited) and type II (noninhibited) by the stimulus. The effect of intravenous ketamine (1, 3, and 10 mg/kg), dextromethorphan (5 mg/kg), and memantine (16 mg/kg) on neuronal responses of these units was measured. Results Spontaneous and evoked neuronal activity to UBD was reduced in a dose-dependent fashion by ketamine. Responses to nonnoxious cutaneous stimuli were also significantly reduced after treatment. Dextromethorphan inhibited neuronal activity evoked by UBD in type I neurons. A similar selective effect of treatment on type I versus type II neurons was observed after intravenous ketamine and memantine. Conclusions Intravenous ketamine produces dose-dependent inhibition of the spinal cord neuronal responses evoked by UBD. All three N-methyl-D-aspartate receptor antagonists showed selective effects on spinal cord neurons subject to counterirritation. This neurophysiologic evidence supports a spinally mediated analgesic effect of ketamine in this model of urinary bladder nociception, an effect likely caused by N-methyl-D-aspartate receptor antagonism.

scholarly journals Direct evidence of amyloid precursor–like protein 1 trans interactions in cell–cell adhesion platforms investigated via fluorescence fluctuation spectroscopy

2017 ◽  
Vol 28 (25) ◽  
pp. 3609-3620 ◽  
Author(s):  
Valentin Dunsing ◽  
Magnus Mayer ◽  
Filip Liebsch ◽  
Gerhard Multhaup ◽  
Salvatore Chiantia
Keyword(s):  
Molecular Mechanisms ◽  
Direct Evidence ◽  
Transmembrane Protein ◽  
Membrane Vesicles ◽  
Correlation Spectroscopy ◽  
Type I ◽  
Plasma Membrane Vesicles ◽  
Fluorescence Fluctuation Spectroscopy ◽  
Human Embryonic Kidney Cells ◽  
Cell Cell

The amyloid precursor–like protein 1 (APLP1) is a type I transmembrane protein that plays a role in synaptic adhesion and synaptogenesis. Past investigations indicated that APLP1 is involved in the formation of protein–protein complexes that bridge the junctions between neighboring cells. Nevertheless, APLP1–APLP1 trans interactions have never been directly observed in higher eukaryotic cells. Here, we investigated APLP1 interactions and dynamics directly in living human embryonic kidney cells using fluorescence fluctuation spectroscopy techniques, namely cross-correlation scanning fluorescence correlation spectroscopy and number and brightness analysis. Our results show that APLP1 forms homotypic trans complexes at cell–cell contacts. In the presence of zinc ions, the protein forms macroscopic clusters, exhibiting an even higher degree of trans binding and strongly reduced dynamics. Further evidence from giant plasma membrane vesicles suggests that the presence of an intact cortical cytoskeleton is required for zinc-induced cis multimerization. Subsequently, large adhesion platforms bridging interacting cells are formed through APLP1–APLP1 trans interactions. Taken together, our results provide direct evidence that APLP1 functions as a neuronal zinc-dependent adhesion protein and allow a more detailed understanding of the molecular mechanisms driving the formation of APLP1 adhesion platforms.

Type II glucocorticoid receptors in the CNS regulate metabolism in ob/ob mice independent of protein synthesis

1994 ◽  
Vol 266 (3) ◽  
pp. E427-E432
Author(s):  
H. L. Chen ◽  
D. R. Romsos
Keyword(s):  
Protein Synthesis ◽  
Glucocorticoid Receptors ◽  
Type I ◽  
Intracerebroventricular Injection ◽  
Type Ii ◽  
Ru 486 ◽  
Brown Adipose ◽  
Brown Adipose Tissue Thermogenesis ◽  
Cerebral Protein Synthesis ◽  
Corticoid Receptor

A single intracerebroventricular injection of dexamethasone rapidly (within 30 min) decreases brown adipose tissue thermogenesis by 25% as assessed by GDP binding and increases plasma insulin twofold in adrenalectomized ob/ob mice. The present study investigated the type of corticoid receptor(s) that mediate these effects and determined whether protein synthesis was necessary for expression of these glucocorticoid actions in ob/ob mice. Intracerebroventricular injection of aldosterone (a type I-corticoid receptor agonist) was ineffective in altering peripheral metabolism in adrenalectomized ob/ob mice, whereas RU-486 (a type II-corticoid receptor antagonist) abolished the effects of dexamethasone. Thus type II-like corticoid receptors, not type I receptors, mediated the rapid effects of dexamethasone in adrenalectomized ob/ob mice. Anisomycin (0.5 mg) administered subcutaneously almost completely suppressed (-92%) cerebral protein synthesis, but anisomycin did not abolish the rapid effects of dexamethasone in adrenalectomized ob/ob mice. Thus protein synthesis is not a prerequisite for rapid effects of dexamethasone in adrenalectomized ob/ob mice.

Aldosterone receptors in A6 cells: physicochemical characterization and autoradiographic study

1989 ◽  
Vol 257 (4) ◽  
pp. C665-C677 ◽  
Author(s):  
M. Claire ◽  
B. Machard ◽  
M. Lombes ◽  
M. E. Oblin ◽  
J. P. Bonvalet ◽  
...  
Keyword(s):  
Glucocorticoid Receptors ◽  
Physicochemical Characterization ◽  
Sedimentation Coefficient ◽  
Size Exclusion ◽  
Type I ◽  
Type Ii ◽  
Homogeneous Population ◽  
Binding Characteristics ◽  
A6 Cells ◽  
Receptor Complexes

The A6 cell line is derived from the kidney of Xenopus laevis. Aldosterone increases sodium transport across A6 cell epithelia. In the present study, aldosterone binding characteristics were studied in A6 cell cytosol. Both type I (mineralocorticoid) and type II (glucocorticoid) receptors are present in the cytosolic fraction of these cells. Aldosterone and corticosterone had a high affinity for type I sites (Kd = 1.25 and 0.16 nM, respectively) and a lower affinity for type II sites (Kd = 39 and 10 nM, respectively). Testosterone and estradiol did not compete for aldosterone binding. RU 26988, a highly specific glucocorticoid agonist, competed with aldosterone for type II but not for type I sites. Hydrodynamic parameters of both type I and type II corticosterone receptor complexes were identical. Their Stokes radius was approximately 6 nm, as estimated by high-performance size-exclusion chromatography, and their sedimentation coefficient determined by ultracentrifugation on glycerol gradients was approximately 9s. The molecular mass calculated from these parameters was approximately 200 kDa, a value that is very close to the value estimated for nontransformed mineralocorticoid and glucocorticoid receptors of other species. The [3H]aldosterone labeling of intact A6 cells was examined by autohistoradiography. At every concentration tested (2, 20, and 50 nM), all cells were found to be specifically labeled in both cytoplasm and nucleus. At 20 nM, in the presence of an excess of RU 26988, labeling was also detected. At every concentration the labeling data was compatible with a Gaussian distribution, indicating that A6 cells correspond to a homogeneous population with regard to aldosterone binding and that probably both type I and type II sites are present in the same cells.

Glucocorticoid receptors in PVN: interactions with NE, NPY, and Gal in relation to feeding

1993 ◽  
Vol 265 (5) ◽  
pp. E794-E800 ◽  
Author(s):  
D. L. Tempel ◽  
S. F. Leibowitz
Keyword(s):  
Glucocorticoid Receptors ◽  
Steroid Receptors ◽  
Carbohydrate Intake ◽  
Type I ◽  
Fat Intake ◽  
Type Ii ◽  
Stimulatory Action ◽  
Carbohydrate Ingestion ◽  
Ru 486 ◽  
Ru 28318

Norepinephrine (NE) and neuropeptide Y (NPY) potentiate carbohydrate ingestion after injection into the paraventricular nucleus (PVN), whereas injection of galanin (Gal) potentiates fat intake. The present study examines the relation between these neurochemically induced feeding behaviors and the adrenal steroids acting locally within the PVN. Results demonstrate that PVN NE- and NPY-induced carbohydrate intake is abolished by adrenalectomy surgery (ADX) and by local PVN implants of the type II receptor antagonist RU-486. Carbohydrate intake in response to PVN NE or NPY injection is unaffected by the type I antagonist RU-28318. In contrast, the stimulatory effect of PVN Gal injection on fat intake is unchanged by surgical ADX or by PVN administration of RU-486 or RU-28318, suggesting that the stimulatory action of Gal on fat ingestion occurs independently of corticosterone (Cort) and of PVN type I or type II steroid receptors. It is concluded that endogenous Cort has a permissive effect on the carbohydrate feeding responses elicited by NE and NPY in the PVN and that this interaction is mediated by type II glucocorticoid receptors within this nucleus.

Upregulation of sodium conductive pathways in alveolar type II cells in sublethal hyperoxia

1994 ◽  
Vol 266 (1) ◽  
pp. L30-L37 ◽  
Author(s):  
J. F. Haskell ◽  
G. Yue ◽  
D. J. Benos ◽  
S. Matalon
Keyword(s):  
Membrane Vesicles ◽  
Exposure Period ◽  
Na Channel ◽  
Alveolar Type ◽  
Type Ii ◽  
Na Transport ◽  
Plasma Membrane Vesicles ◽  
Outward Currents ◽  
Na Currents

We investigated whether exposure of rats to sublethal hyperoxia (85% O2 for 7 days) raises the levels of proteins antigenically related to Na+ channels in alveolar type II (ATII) cells and, if so, whether this rise was accompanied by an increase in conductive Na+ transport in vitro. ATII cells were isolated from the lungs of these rats at the end of the exposure period. In Western blot studies, a polyclonal antibody raised against Na+ channel protein (NaAb), recognized in a specific manner a 135 +/- 10 kDa polypeptide in plasma membrane vesicles of ATII cells from both control and oxygen-exposed rats. However, higher levels of immunoreactivity were seen in ATII cells from oxygen-exposed rats. When ATII cells were patched in the whole cell mode using symmetrical solutions (150 mM Na(+)-glutamate), outward rectified Na+ currents were observed. When corrected for cell capacitance, both inward and outward currents of ATII cells from rats exposed to hyperoxia were significantly higher than control. Addition of either 1 microM amiloride or 1 microM 5-(N-ethyl-N-isopropyl)-2'-4'-amiloride in the bath solution decreased the magnitude of outward currents of both control and hyperoxic ATII cells by approximately 50%. Taken together, these results indicate that exposure of rats to sublethal hyperoxia results in upregulation of ATII cell conductive pathways with low affinity to amiloride and increased Na+ transport. This may be an early adaptive response that limits the degree of alveolar edema in injured lungs.

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