ATP-MgCl2 treatment after trauma-hemorrhage/resuscitation increases hepatocyte P2-purinoceptor binding capacity

1994 ◽  
Vol 266 (6) ◽  
pp. R1810-R1815
Author(s):  
M. S. Mahmoud ◽  
P. Wang ◽  
S. R. Hootman ◽  
S. S. Reich ◽  
I. H. Chaudry
Keyword(s):  
Binding Capacity ◽  
Scatchard Analysis ◽  
Binding Characteristics ◽  
Beneficial Effects ◽  
High Affinity ◽  
Receptor Component ◽  
Receptor Dynamics ◽  
Maximum Binding Capacity ◽  
High Affinity Receptor ◽  
Affinity Receptor

Although our studies indicate that P2-purinoceptor binding capacity decreases after hemorrhage and resuscitation, it is not known whether ATP-MgCl2 administration after hemorrhage has any beneficial effects on the receptor dynamics. To study this, we performed laparotomy (i.e., trauma induced) on rats and bled them to and maintained them at a mean arterial pressure of 40 mmHg until 40% of maximum bleedout volume was returned in the form of Ringer lactate (RL). The animals were then resuscitated with 3 times the volume of maximum bleedout with RL over 45 min followed by 2 times RL along with ATP-MgCl2 (50 mumol/kg body wt) over 95 min. Hepatocytes were isolated at 4, 17, and 27 h after resuscitation. P2-purinoceptor binding characteristics were determined by using [alpha-35S]ATP. Scatchard analysis revealed high-affinity and low-affinity receptor components in the hepatocytes isolated from sham-operated or hemorrhaged animals with or without ATP-MgCl2 infusion. ATP-MgCl2 ameliorated and subsequently restored the decreased maximum binding capacity (Bmax) of the high-affinity receptor component and significantly improved Bmax of the low-affinity receptor component. ATP-MgCl2 administration also produced a progressive enhancement in the affinity of the low-affinity receptor component. Thus the beneficial effects of ATP-MgCl2 observed after trauma-hemorrhage and resuscitation may be, in part, due to the restoration of P2-purinoceptor binding capacity and the enhancement of the receptor affinity.

Downregulation of hepatocyte P2-purinoceptor binding capacity after trauma-hemorrhage/resuscitation

1994 ◽  
Vol 266 (6) ◽  
pp. R1804-R1809
Author(s):  
M. S. Mahmoud ◽  
P. Wang ◽  
S. R. Hootman ◽  
S. S. Reich ◽  
I. H. Chaudry
Keyword(s):  
Dissociation Constants ◽  
Binding Capacity ◽  
Isolated Hepatocytes ◽  
Scatchard Analysis ◽  
Midline Laparotomy ◽  
Binding Characteristics ◽  
Shed Blood ◽  
P2 Purinoceptors ◽  
Altered Glucose ◽  
Affinity Receptor

Although P2-purinoceptors play an important role in the regulation of liver metabolism under normal conditions, it is not known if trauma-hemorrhage and resuscitation have any effects on such receptors. To study this, we performed a 5-cm midline laparotomy (i.e., trauma induced) on rats and then bled them to and maintained them at a mean arterial pressure of 40 mmHg until 40% of maximum bleedout volume was returned in the form of Ringer lactate (RL). The animals were then resuscitated with 3x the volume of shed blood with RL over 45 min followed by 2x RL over 95 min. Hepatocytes were isolated at the time of maximum bleedout or at 0, 4, 17, and 27 h after the completion of crystalloid resuscitation. P2-purinoceptor binding characteristics were determined in the isolated hepatocytes by using [alpha-35S]ATP. Scatchard analysis revealed high- and low-affinity components of P2-purinoceptors in hepatocytes from sham-operated as well as hemorrhaged and resuscitated animals. The maximum binding capacity (Bmax) of the high-affinity receptor component decreased at the time of maximum bleedout and at 4, 17, and 27 h after resuscitation. In addition to this, the Bmax of low-affinity receptor components also decreased at 4-27 h after resuscitation. In contrast, the dissociation constants of both receptor components were not altered. Because hemorrhagic shock produces abnormalities in glucose metabolism, the downregulation of hepatocyte P2-purinoceptor Bmax may be responsible for the altered glucose homeostasis under such conditions.

Corticosteroid-binding studies in cytosol of colonic mucosa of the rat

1981 ◽  
Vol 240 (6) ◽  
pp. G417-G423
Author(s):  
E. T. Marusic ◽  
J. P. Hayslett ◽  
H. J. Binder
Keyword(s):  
Colonic Mucosa ◽  
Steroid Receptors ◽  
Binding Capacity ◽  
Potential Difference ◽  
Scatchard Analysis ◽  
Binding Studies ◽  
Minimal Dose ◽  
High Affinity Receptor ◽  
Affinity Receptor ◽  
Cytosolic Receptor

Cytosolic binding of [3H]dexamethasone was studied in the colon of the rat. [3H]dexamethasone binding was rapid and stable at 4 degrees C for 240 min. Scatchard analysis revealed a Kd of 6.2 +/- 0.5 X 10(-9) M and a binding capacity of 149 +/- 6.4 fmol/mg cytosolic protein (100,000-g fraction). Although dexamethasone inhibited [3H]dexamethasone binding more than that of aldosterone, [3H]aldosterone binding was inhibited equally by both aldosterone and dexamethasone. The relative order of potency of other steroids to inhibit [3H]dexamethasone binding was: dexamethasone greaterthan progesterone greater than spironolactone greater than aldosterone greater than corticosterone greater than cortexolone greater than estradiol. In other experiments, low doses of dexamethasone and aldosterone were infused into adrenalectomized animals to determine functional importance of these cytosolic steroid receptors. One-hour infusion of aldosterone at 2 micrograms/100 g body wt, which was the minimal dose of dexamethasone that increased transmural potential difference, did not alter the potential difference. These studies demonstrate the presence of a cytosolic receptor for dexamethasone and suggest that the action of dexamethasone on electrolyte transport in adrenalectomized animals is not mediated by the mineralocorticoid type of receptor and may be mediated by the specific high-affinity receptor for dexamethasone.

scholarly journals Effects of Midgut-Protein-Preparative and Ligand Binding Procedures on the Toxin Binding Characteristics of BT-R1, a Common High-Affinity Receptor in Manduca sexta for Cry1A Bacillus thuringiensis Toxins

1998 ◽  
Vol 64 (6) ◽  
pp. 2158-2165 ◽  
Author(s):  
Timothy P. Keeton ◽  
Brian R. Francis ◽  
Walid S. A. Maaty ◽  
Lee A. Bulla
Keyword(s):  
Ligand Binding ◽  
Manduca Sexta ◽  
Protein S ◽  
Receptor Protein ◽  
Common Mechanism ◽  
Binding Characteristics ◽  
Toxin Binding ◽  
High Affinity ◽  
High Affinity Receptor ◽  
Affinity Receptor

ABSTRACT The identity of the physiologically important Cry1A receptor protein(s) in the lepidopteran Manduca sexta has been a matter of dispute due to the multiple proteins which bind the Cry1Ac toxin. Cry1Aa, Cry1Ab, and Cry1Ac exhibit essentially identical toxicities toward M. sexta larvae and show a high degree of sequence and presumed structural identities. These similarities make it likely that there is a common mechanism of toxicity in these lepidopteran-specific toxins in terms of both mode of action and the receptor proteins through which these toxins exert their lepidopteran-specific toxicity. Investigators in our laboratory previously demonstrated that the cloned 210-kDa glycoprotein BT-R1 binds all three Cry1A toxins (T. P. Keeton and L. A. Bulla, Jr., Appl. Environ. Microbiol. 63:3419–3425, 1997). This protein remains a common binding protein even after being subjected to various midgut membrane preparation and processing protocols. The method used to isolate proteins from the M. sexta larval midgut in no significant way affects the results of ligand binding and vacuum blotting experiments, and we have been unable to detect specific, high-affinity binding of any Cry1A toxin to Cry1Ac binding proteins other than BT-R1. Alterations in blot substrate and blocking, hybridization, and washing buffers support these conclusions. Collectively, these results indicate that inM. sexta the cadherin-like BT-R1 protein is a common high-affinity receptor protein for the Cry1A family of toxins.

Fasting alters somatostatin binding to liver membranes of rainbow trout (Oncorhynchus mykiss)

1996 ◽  
Vol 150 (2) ◽  
pp. 179-186 ◽  
Author(s):  
M J Pesek ◽  
M A Sheridan
Keyword(s):  
Rainbow Trout ◽  
Binding Sites ◽  
Binding Capacity ◽  
Specific Binding ◽  
Scatchard Analysis ◽  
Binding Characteristics ◽  
High Affinity ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
C Terminus ◽  
Liver Membranes

Abstract Somatostatins are a diverse family of peptides that influence various aspects of animal growth, development, and metabolism. Recent work in our laboratory has shown that somatostatins stimulate hepatic lipolysis in rainbow trout. In this study we characterized somatostatin-binding sites in trout hepatic membrane preparations. We also examined changes in binding characteristics brought about by food deprivation. Binding of [Tyr11]-somatostatin-14 (SS-14) was saturable, reversible, and time- and temperature-dependent. Under optimal conditions, [Tyr11]-SS-14 specific binding averaged 5·7 ± 0·3%. While SS-14 and SS-28 (an N-terminally extended form of SS-14 and derived from the same gene as SS-14) displaced [Tyr11]-SS-14 specific binding (ED50 values of approximately 50 nm and 100 nm respectively), salmon SS-25 (containing [Tyr7,Gly10]-SS-14 at its C terminus and presumably derived from a gene different from that giving rise to SS-14/SS-28), except at pharmacological concentrations, did not. Significant specific binding was also detected in brain, esophagus, stomach, upper and lower intestine, pancreas, and adipose tissue. Scatchard analysis suggested the existence of two classes of hepatic somatostatin-binding sites: a high-affinity site with a Kd of 23 nm and Bmax of 1·4 pmol/mg protein and a low-affinity site with a Kd of 379 nm and Bmax of 4·9 pmol/mg protein. Fasting resulted in reduced growth and elevated plasma levels of SS-14 compared with fed animals. SS-14 binding capacity of the high-affinity class in liver membranes isolated from fasted fish increased by 120% over that from fed counter-parts. No difference in Kd for the high-affinity binding class or in either Kd or Bmax of the low-affinity class was noted between fasted and fed animals. These data support the role of the liver as a target of somatostatin and suggest that fasting enhances hepatic sensitivity to SS-14 binding. Journal of Endocrinology (1996) 150, 179–186

scholarly journals IL-33 and Superantigenic Activation of Human Lung Mast Cells Induce the Release of Angiogenic and Lymphangiogenic Factors

Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 145
Author(s):  
Leonardo Cristinziano ◽  
Remo Poto ◽  
Gjada Criscuolo ◽  
Anne Lise Ferrara ◽  
Maria Rosaria Galdiero ◽  
...  
Keyword(s):  
Mast Cells ◽  
Human Lung ◽  
Protein A ◽  
Protein L ◽  
Variable Regions ◽  
Prolonged Incubation ◽  
High Affinity ◽  
High Affinity Receptor ◽  
Affinity Receptor ◽  
Pleiotropic Functions

Human lung mast cells (HLMCs) express the high-affinity receptor FcεRI for IgE and are strategically located in different compartments of human lung, where they play a role in several inflammatory disorders and cancer. Immunoglobulin superantigens (e.g., protein A of Staphylococcus aureus and protein L of Peptostreptococcus magnus) bind to the variable regions of either the heavy (VH3) or light chain (κ) of IgE. IL-33 is a cytokine expressed by epithelial cells that exerts pleiotropic functions in the lung. The present study investigated whether immunoglobulin superantigens protein A and protein L and IL-33 caused the release of inflammatory (histamine), angiogenic (VEGF-A) and lymphangiogenic (VEGF-C) factors from HLMCs. The results show that protein A and protein L induced the rapid (30 min) release of preformed histamine from HLMCs. By contrast, IL-33 did not induce the release of histamine from lung mast cells. Prolonged incubation (12 h) of HLMCs with superantigens and IL-33 induced the release of VEGF-A and VEGF-C. Preincubation with IL-33 potentiated the superantigenic release of histamine, angiogenic and lymphangiogenic factors from HLMCs. Our results suggest that IL-33 might enhance the inflammatory, angiogenic and lymphangiogenic activities of lung mast cells in pulmonary disorders.

The Temporal Distribution of the 1α,25-Dihydroxycholecalciferol Receptor in the Rat Jejunal Villus

1984 ◽  
Vol 67 (3) ◽  
pp. 285-290 ◽  
Author(s):  
S. D. H. Chan ◽  
D. Atkins
Keyword(s):  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Calcium Absorption ◽  
Sedimentation Coefficient ◽  
Temporal Distribution ◽  
High Affinity ◽  
High Affinity Receptor ◽  
Affinity Receptor ◽  
Cell Fractions ◽  
Crypt Cells

1. The distribution of the 1α,25-dihydroxycholecalciferol receptor was studied in enterocytes isolated from the upper, mid and lower villus and crypt cells of the jejunum of normal and rachitic rats. 2. In all cell fractions a high-affinity receptor (KD ⋍ 0.07 nmol/l) with a sedimentation coefficient of 3.5S was demonstrated. 3. In normal rats there was a 60% reduction in receptor numbers in crypt cells compared with the mid and upper villous cells. 4. Vitamin D deficiency led to a reduction in receptor numbers in all cell fractions (45% upper villus, 78% crypt cells). 5. The data are compatible with the concept of calcium absorption occurring in the differentiated villous cells and also account for the reduction in absorption in rachitic animals.

scholarly journals Neuropilin-2, a Novel Member of the Neuropilin Family, Is a High Affinity Receptor for the Semaphorins Sema E and Sema IV but Not Sema III

Neuron ◽  
1997 ◽  
Vol 19 (3) ◽  
pp. 547-559 ◽  
Author(s):  
Hang Chen ◽  
Alain Chédotal ◽  
Zhigang He ◽  
Corey S Goodman ◽  
Marc Tessier-Lavigne
Keyword(s):  
High Affinity ◽  
High Affinity Receptor ◽  
Affinity Receptor
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