Vasodilation and glomerular binding of adrenomedullin in rabbit kidney are not CGRP receptor mediated

The polypeptide adrenomedullin (ADM) was infused systemically to conscious rabbits to elucidate its actions on overall circulation and especially the renovascular bed and the formation and/or release of hormones important for body fluid homeostasis, including adrenocortical steroids. ADM lowered mean arterial pressure from 71.5 +/- 3.2 to 64.7 +/- 3.2 mmHg only at the highest dose of 25 pmol.min-1.kg-1 infused intravenously for 20 min and concomitantly induced tachycardia, possibly due to both baroreflex activation and direct cardiostimulatory effects. Renal blood flow (RBF) determined in rabbits chronically equipped with a perivascular ultrasonic flow probe increased from 55.4 +/- 2.1 to 67.4 +/- 2.7 and from 58.2 +/- 3.5 to 75.2 +/- 6.0 ml/min at ADM infusions of 5 and 25 pmol.min-1.kg-1, respectively. The elevation in RBF persisted even in the presence of the calcitonin gene-related peptide (CGRP1 receptor antagonist CGRP-(8-37). Of all osmoregulatory hormones tested, only corticosterone (Cort) plasma concentration increased in response to the highest ADM dose from 17.6 +/- 3.1 to 38.9 +/- 6.2 ng/ml, probably due to haroreflex activation. Subdepressor doses of ADM, however, caused a mild reduction in circulating Cort. Expression of functional high-affinity binding sites specific for ADM in vitro could be demonstrated for the renal artery and outer cortical glomeruli using 125I-labeled rat ADM as radioligand and determination of cellular adenosine 3',5'-cyclic monophosphate (cAMP) formation within the glomeruli. The ineffectiveness of CGRP-(8-37) to displace radiolabeled ADM from its binding sites, to inhibit ADM-induced glomerular cAMP formation, and to prevent ADM-induced renal vasodilation supports the hypothesis of ADM altering renal hemodynamics by interacting with ADM- and not CGRP-specific membrane receptors.

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In vitro determination of the effect of indoleglycerol phosphate on the interaction of purified TrpI protein with its DNA-binding sites.

Journal of Bacteriology ◽

10.1128/jb.173.5.1590-1597.1991 ◽

1991 ◽

Vol 173 (5) ◽

pp. 1590-1597 ◽

Cited By ~ 15

Author(s):

M Chang ◽

I P Crawford

Keyword(s):

Dna Binding ◽

Binding Sites ◽

Dna Binding Sites

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Glucocorticoids directly affect spectrophotometry of bilirubin in amniotic fluid.

Clinical Chemistry ◽

10.1093/clinchem/30.5.677 ◽

1984 ◽

Vol 30 (5) ◽

pp. 677-680

Author(s):

A Milwidsky ◽

S Yagel ◽

M Chaouat ◽

M Mayer

Keyword(s):

Amniotic Fluid ◽

Binding Sites ◽

Time Dependent ◽

Hemolytic Disease ◽

Low Concentrations ◽

Chemical Determination ◽

Cautious Interpretation ◽

Layer Chromatography

Abstract Dexamethasone or prednisolone, added in vitro to bilirubin-containing amniotic fluid, produces a time-dependent decrease in the 450-nm absorbance of the pigment. Neither the chemical determination of bilirubin in amniotic fluid nor the lecithin/sphingomyelin ratio as determined by thin-layer chromatography is affected by these glucocorticoids. The effect probably is not a result of displacement of bilirubin from its binding sites on albumin, because the absorbance of a solution of crystalline bilirubin at 450 nm is unaffected by added bovine serum albumin. Light scattering of amniotic fluid increases slightly when dexamethasone is added, whether or not low concentrations of bilirubin (less than 1.6 mumol/L) are present. Thus the effect on absorbance evidently is not ascribable to supersaturation and formation of a colloidal sol of bilirubin particles. This direct interference of glucocorticoids with the spectrophotometry of bilirubin in amniotic fluid prompts cautious interpretation of such data as an index to the severity of hemolytic disease of the fetus, specifically in cases of Rhesus-isoimmunization that are being treated with glucocorticoids.

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Localization of binding sites for calcitonin gene-related peptide in rat brain by in vitro autoradiography

Neuroscience ◽

10.1016/0306-4522(86)90137-5 ◽

1986 ◽

Vol 19 (4) ◽

pp. 1235-1245 ◽

Cited By ~ 86

Author(s):

P.M. Sexton ◽

J.S. McKenzie ◽

R.T. Mason ◽

J.M. moseley ◽

T.J. Martin ◽

...

Keyword(s):

Rat Brain ◽

Binding Sites ◽

Calcitonin Gene Related Peptide ◽

In Vitro Autoradiography ◽

Related Peptide ◽

Calcitonin Gene

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Autoradiographic determination of dexamethasone binding sites along the rabbit nephron

AJP Renal Physiology ◽

10.1152/ajprenal.1983.244.3.f325 ◽

1983 ◽

Vol 244 (3) ◽

pp. F325-F334 ◽

Cited By ~ 5

Author(s):

N. Farman ◽

A. Vandewalle ◽

J. P. Bonvalet

Keyword(s):

Proximal Tubule ◽

Binding Sites ◽

Specific Binding ◽

Rabbit Kidney ◽

Nuclear Binding ◽

Specific Binding Sites ◽

In Vitro Incubation ◽

Collecting Tubules

Specific binding sites of tritiated dexamethasone ([3H]dex) along the tubule of rabbit kidney were investigated using an autoradiographic method (dry film) on isolated tubular segments. After in vitro incubation of kidney pyramids with [3H]dex (0.15-53 nM) in the presence or absence of an excess (X200) of unlabeled dexamethasone, tubular segments were microdissected and processed for autoradiography. A quantitative analysis of specific labeling over cytoplasm and nuclei was performed. Specific nuclear binding was observed in all tubular segments beyond the pars recta. This binding was dose dependent and reached much higher values than those reported for aldosterone. In the proximal tubule, the specific labeling was also high but remained mostly cytoplasmic. The meaning of these drastically different intracellular localizations is still open to interpretation. Autoradiography was performed after in vivo injection of [3H]dex and [3H]aldosterone. The results were not different from those described here for dexamethasone and from those previously reported for aldosterone after in vitro incubation. We conclude that specific nuclear binding sites for dexamethasone range over the nephron except for proximal tubule, with no great difference among segments, in contrast to specific sites for aldosterone, which are restricted to distal and cortical collecting tubules. The exact significance of the proximal cytoplasmic specific binding of [3H]dex remains to be determined.

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Human Granulocyte LTB4 Production and Respiratory Burst Impaired by Styrene

Alternatives to Laboratory Animals ◽

10.1177/026119298801600106 ◽

1988 ◽

Vol 16 (1) ◽

pp. 23-26

Author(s):

Matteo Valentino ◽

Mario Governa ◽

Isabella Marchiseppe ◽

Isabella Visona'

Keyword(s):

Respiratory Burst ◽

Styrene Oxide ◽

Irreversible Damage ◽

Human Granulocytes ◽

Ltb4 Production ◽

Specific Membrane ◽

Specific Membrane Receptor ◽

In Cells

Human granulocytes (PMN) incubated in vitro with styrene at a concentration of 3.3 x 10-4 M have shown an impairment of leucotriene B4 (LTB4) production and of respiratory burst after stimulation with N-formyl-methyonil-leucyl-phenylalanine peptide (nFMLP), which has a specific membrane receptor. The level of impairment in LTB4 production was lower in cells pretreated for 15 minutes with styrene than in cells treated with styrene and nFMLP simultaneously. Styrene did not cause irreversible damage, because 15 minutes after styrene treatment PMN partially recovered their function. The determination of styrene and styrene oxide, the presumed active metabolite, in the supernatant of cell culture, showed that styrene rapidly enters the cell and only 15 minutes or more after styrene addition was styrene oxide found. On this basis, the action of styrene does not seem to be mediated by metabolites.

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Conformation of Ribosomes from Escherichia Coli

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051062 ◽

1974 ◽

Vol 32 ◽

pp. 210-211

Author(s):

M. Boublik ◽

W. Hellmann ◽

F. Jenkins

Keyword(s):

Binding Sites ◽

Ribosomal Proteins ◽

Fluorescent Dyes ◽

Protein Biosynthesis ◽

Three Dimensional ◽

Spatial Arrangement ◽

Dimensional Structure ◽

Complete Understanding ◽

And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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Reduction of Potassium in Kidney Proximal Tubules to Aid in Electron Probe X-Ray Microanalysis of Calcium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119193 ◽

1985 ◽

Vol 43 ◽

pp. 474-475

Author(s):

A. LeFurgey ◽

P. Ingram ◽

L.J. Mandel

Keyword(s):

Smooth Muscle ◽

Proximal Tubule ◽

Electron Probe ◽

Clinical Applications ◽

Proximal Tubules ◽

Rabbit Kidney ◽

Target Cells ◽

X Ray ◽

Freeze Dried

For quantitative determination of subcellular Ca distribution by electron probe x-ray microanalysis, decreasing (and/or eliminating) the K content of the cell maximizes the ability to accurately separate the overlapping K Kß and Ca Kα peaks in the x-ray spectra. For example, rubidium has been effectively substituted for potassium in smooth muscle cells, thus giving an improvement in calcium measurements. Ouabain, a cardiac glycoside widely used in experimental and clinical applications, inhibits Na-K ATPase at the cell membrane and thus alters the cytoplasmic ion (Na,K) content of target cells. In epithelial cells primarily involved in active transport, such as the proximal tubule of the rabbit kidney, ouabain rapidly (t1/2= 2 mins) causes a decrease2 in intracellular K, but does not change intracellular total or free Ca for up to 30 mins. In the present study we have taken advantage of this effect of ouabain to determine the mitochondrial and cytoplasmic Ca content in freeze-dried cryosections of kidney proximal tubule by electron probe x-ray microanalysis.

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