endothelin-1 and Cadaver

Insulin leads to overexpression of endothelin-1 (ET-1) in the endothelium of insulin-resistant rodents. If this is also the case in equine laminar tissue, this could explain the predisposition of insulin-resistant horses to laminitis.. To investigate the effect of hyperinsulinaemia on metabolism and vascular resistance of the isolated equine digit in a model of extracorporeal perfusion.. Randomised, controlled study with interventional group, with blinded evaluation of histology results.. After exsanguination, equine digits (n = 11) and autologous blood were collected at an abattoir. One digit served as a hyperinsulinaemic pilot limb, 5 digits were assigned to the hyperinsulinaemic perfusion (IP) group and 5 to the control perfusion (CP) group. Digits were perfused for 10 h at a defined perfusion rate of 12 ml/min/kg. After the first hour of perfusion (equilibration period), insulin was added to the reservoir of the IP digits. Perfusion pressure, glucose consumption, lactate and lactate dehydrogenase were monitored. Vascular resistance was calculated as perfusion pressure (in millimetres of mercury) in relation to the flow rate (in millilitres per minute). After perfusion, histology samples of the dorsal hoof wall (haematoxylin & eosin or periodic acid-Schiff) were evaluated. Immunohistology with a polyclonal rabbit-derived anti-endothelin antibody was used for detection of ET-1.. In the IP group, the mean insulin concentration in the plasma of the perfusate was 142 ± 81 μiu/ml, while insulin concentration was <3 μiu/ml in the CP group. Mean vascular resistance was significantly higher (P<0.01) in the IP group (2.04 ± 1.13 mmHg/ml/min) than in the CP group (1.31 ± 0.55 mmHg/ml/min). Histology of the IP group samples showed significantly more vessels with an open lumen, increased width of the secondary epidermal lamellae and formation of oedema. In the lamellar vessels (veins and arteries) and nerve fibres, ET-1 expression was much more prominent in the IP group than in the CP group samples.. Short-term hyperinsulinaemia leads to increased vascular resistance in the equine digit and increased expression of ET-1 in the laminar tissue.

Topics: Animals; Cadaver; Endothelin-1; Gene Expression Regulation; Horses; Hyperinsulinism; Insulin; Perfusion

Analysis of aqueous humor from patients with primary open-angle glaucoma (POAG) revealed marked increases in the content of endothelin-1 (ET-1) and transforming growth factor-beta (TGF-β). We determined the consequences of TGF-β signaling on ET-1 expression and secretion by human trabecular meshwork (TM) cells.. Primary or transformed (NTM5 and GTM3) human TM cells conditioned in serum-free media were incubated in the absence or presence of TGF-β1 or -β2. Relative changes in preproendothelin (ppET)-1 mRNA content and secreted ET-1 peptide were quantified by real-time PCR and ELISA, respectively. In some experiments, TGF-β or ET-1 receptor antagonists, or Rho G-protein inhibitors, were evaluated for effects on TGF-β signaling. Filamentous actin organization was visualized by phalloidin.. Primary or transformed human TM cells cultured in the presence of TGF-β1 or -β2 exhibit a marked (>8-fold) increase in ppET-1 mRNA content compared to vehicle controls. Coincubation with SB-505124, an inhibitor of TGFβRI/ALK-5 signaling, prevented TGF-β-mediated ppET-1 mRNA expression. In contrast, coincubation with ET(A) (BQ-123) or ET(B) (BQ-788) receptor antagonists had no effect on TGF-β-mediated ppET-1 mRNA expression. TGF-β1 and -β2 each elicited a robust (>7-fold) secretion of ET-1 while enhancing stress fiber organization. Inhibition of Rho signaling attenuated TGF-β-mediated increases in ppET-1 mRNA content, ET-1 secretion, and stress fiber organization.. TGF-β, signaling through the TGFβRI/ALK-5 receptor, elicits marked increases in ET-1 mRNA content and ET-1 secretion from cultured primary or transformed human TM cells. Elevated levels of TGF-β2 present in AH of POAG patients may elevate intraocular pressure, in part, by eliciting aberrant Rho G-protein dependent cell contraction, and increasing ET-1 synthesis and secretion, in human TM cells.

Topics: Actins; Analysis of Variance; Benzodioxoles; Cadaver; Cell Line, Transformed; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Humans; Imidazoles; Lovastatin; Pyridines; Real-Time Polymerase Chain Reaction; Recombinant Proteins; RNA, Messenger; Signal Transduction; Trabecular Meshwork; Transforming Growth Factor beta2

This study was designed to analyze the distribution and localization of endothelin-1 (ET-1) and ET receptors (ET(A) and ET(B)) at different stages of human atherosclerotic lesions by immunohistochemistry. Compared with ET(A) receptors, there was increased immunoreactivity of ET-1 and ET(B) receptor in both unfoamy and foamy macrophages and T lymphocytes in fatty streak and fibrous plaque lesions. In addition, medial SMCs located just beneath the foam cell lesions revealed a higher intensity of ET(B) receptor immunoreactivity than those located beneath the normal-looking intima without foam cells. In fibrous plaques, intimal SMCs near foam cells showed an increased density of ET receptors with predominant ET(B) immunoreactivity. In the areas where SMCs showed ET(B) receptor, ET-1 immunoreactivity was also enhanced. These results suggest that accumulation of foamy macrophages and T lymphocytes may modulate the switching of ET receptor subtypes from ET(A) to ET(B) in vascular SMCs. and that the enhanced ET system mediated by ET(B) receptors may play active roles in the progression of atherosclerosis.

Topics: Adolescent; Adult; Aged; Aorta; Arteriosclerosis; Cadaver; Child; Child, Preschool; Culture Techniques; Cytoplasm; Endothelin-1; Female; Foam Cells; Humans; Immunohistochemistry; Macrophages; Male; Middle Aged; Muscle, Smooth, Vascular; Receptor, Endothelin B; Receptors, Endothelin; Sensitivity and Specificity; Severity of Illness Index; T-Lymphocytes