Endothelium-dependent relaxation and experimental atherosclerosis in the rabbit aorta

1986 ◽  
Vol 64 (11) ◽  
pp. 1451-1453 ◽  
Author(s):  
N. Sreeharan ◽  
R. L. Jayakody ◽  
M. P. J. Senaratne ◽  
A. B. R. Thomson ◽  
C. T. Kappagoda
Keyword(s):  
Rabbit Aorta ◽  
Experimental Atherosclerosis ◽  
Isometric Tension ◽  
Dependent Manner ◽  
Bicarbonate Buffer ◽  
New Zealand White Rabbits ◽  
Set Up ◽  
And Control ◽  
Dose Dependent ◽  
Endothelium Dependent Relaxation

This study was undertaken to determine whether the production or release of the endothelium-dependent relaxatory factor is impaired in atherosclerotic New Zealand White rabbits. Atherosclerosis was induced by feeding a diet containing 2% cholesterol for 6 weeks. The production or release of endothelium-dependent relaxatory factor was assayed as follows. A 5-cm length of aorta donor was perfused with Krebs–bicarbonate buffer and the perfusate drained over a deendothelialized ring of recipient aorta set up for recording isometric tension. The recipient was precontracted with norepinephrine (0.2 μmol/L) in the perfusate. When acetylcholine was added to the perfusate, the recipient relaxed in a dose-dependent manner. This assay was used to compare the relaxatory responses produced in recipient rings by adding acetylcholine to donors from atherosclerotic and control rabbits. The relaxation produced by atherosclerotic donors were smaller than those generated by control donors (16.5 ± 4.9 vs. 32.7 ± 5.3%; n = 10, p < 0.05). It is suggested that in atherosclerotic rabbits the ability of aortic endothelium to produce or release endothelium-dependent relaxatory factor is impaired.

scholarly journals Efficacy of Synthetic Furanones on Listeria monocytogenes Biofilm Formation

Foods ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 647 ◽  
Author(s):  
Pedro Rodríguez-López ◽  
Andrea Emparanza Barrenengoa ◽  
Sergio Pascual-Sáez ◽  
Marta López Cabo
Keyword(s):  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Epifluorescence Microscopy ◽  
Dependent Manner ◽  
Antifouling Activity ◽  
Aisi 316 ◽  
Novel Strategy ◽  
And Control ◽  
Acylated Homoserine Lactones ◽  
Dose Dependent

Furanones are analogues of acylated homoserine lactones with proven antifouling activity in both Gram-positive and Gram-negative bacteria though the interference of various quorum sensing pathways. In an attempt to find new strategies to prevent and control Listeria monocytogenes biofilm formation on stainless steel (SS) surfaces, different concentrations of six synthetic furanones were applied on biofilms formed by strains isolated from food, environmental, and clinical sources grown onto AISI 316 SS coupons. Among the furanones tested, (Z-)-4-Bromo-5-(bromomethylene)-2(5H)-furanone and 3,4-Dichloro-2(5H)-furanone significantly (p < 0.05) reduced the adhesion capacity (>1 log CFU cm−2) in 24 h treated biofilms. Moreover, individually conducted experiments demonstrated that (Z-)-4-Bromo-5-(bromomethylene)-2(5H)-furanone was able to not only significantly (p < 0.05) prevent L. monocytogenes adhesion but also to reduce the growth rate of planktonic cells up to 48 h in a dose-dependent manner. LIVE/DEAD staining followed by epifluorescence microscopy visualisation confirmed these results show an alteration of the structure of the biofilm in furanone-treated samples. Additionally, it was demonstrated that 20 µmol L−1 of 3,4-Dichloro-2(5H)-furanone dosed at 0, 24 and 96 h was able to maintain a lower level of adhered cells (>1 log CFU cm−2; p < 0.05). Since furanones do not pose a selective pressure on bacteria, these results represent an appealing novel strategy for the prevention of L. monocytogenes biofilm grown onto SS.

Persistent impairment of endothelium-dependent relaxation to acetylcholine and progression of atherosclerosis following 6 weeks of cholesterol feeding in the rabbit

1989 ◽  
Vol 67 (11) ◽  
pp. 1454-1460 ◽  
Author(s):  
Laal Jayakody ◽  
Manohara P. J. Senaratne ◽  
Alan B. R. Thomson ◽  
Nadarajan Sreeharan ◽  
C. Tissa Kappagoda
Keyword(s):  
Rabbit Aorta ◽  
Atherogenic Diet ◽  
Acute Stage ◽  
Standard Laboratory ◽  
Cholesterol Feeding ◽  
Functional Abnormality ◽  
New Zealand White Rabbits ◽  
Standard Laboratory Diet ◽  
Endothelium Dependent Relaxation ◽  
Progression Of Atherosclerosis

The synthesis and (or) release of endothelium-dependent relaxant factor released by acetylcholine is impaired in New Zealand white rabbits fed an atherogenic diet. Experiments were designed to investigate whether the synthesis and (or) release of the endothelium-dependent relaxant factor from rabbit aortas are restored after reversal from an atherogenic diet to a non-atherogenic diet. Atherosclerosis was induced by feeding a diet containing lipids and 2% cholesterol for 6 weeks. Rabbits were sacrificed after 6 weeks on the atherogenic diet and 36 weeks after return to a standard laboratory diet. Synthesis and (or) release of the factor from the thoracic aorta was assayed using a bioassay system. The relaxant responses produced in the assay tissue were impaired both in the acute stage and after 36 weeks on non-atherogenic food. This impaired relaxation is probably due to a persistent functional abnormality in the aortic endothelium resulting in the failure to synthesize and (or) release endothelium-dependent relaxation factor 36 weeks after induction of atherosclerosis.Key words: endothelium dependent relaxation, rabbit aorta, atherosclerosis, regression, cholesterol feeding.

Ascorbate enhancement of H1 histamine receptor sensitivity coincides with ascorbate oxidation inhibition by histamine receptors

2006 ◽  
Vol 291 (5) ◽  
pp. C977-C984 ◽  
Author(s):  
Patrick F. Dillon ◽  
Robert S. Root-Bernstein ◽  
Charles M. Lieder
Keyword(s):  
Oxidation Rate ◽  
Rabbit Aorta ◽  
Keyhole Limpet Hemocyanin ◽  
Histamine Receptor ◽  
Histamine Receptors ◽  
Dependent Manner ◽  
Receptor Membrane ◽  
Ascorbate Concentration ◽  
Wet Weight ◽  
Dose Dependent

Ascorbate has previously been shown to enhance both α1- and β2-adrenergic activity. This activity is mediated by ascorbate binding to the extracellular domain of the adrenergic receptor, which also decreases the oxidation rate of ascorbate. H1 histamine receptors have extracellular agonist or ascorbate binding sites with strong similarities to α1- and β2-adrenergic receptors. Physiological concentrations of ascorbate (50 μM) significantly enhanced histamine contractions of rabbit aorta on the lower half of the histamine dose-response curve, increasing contractions of 0.1, 0.2, and 0.3 μM histamine by two- to threefold. Increases in ascorbate concentration significantly enhanced 0.2 μM histamine (5–500 μM ascorbate) and 0.3 μM histamine (15–500 μM ascorbate) in a dose-dependent manner. Histamine does not measurably oxidize over 20 h in oxygenated PSS at 37°C. Thus the ascorbate enhancement is independent of ascorbate's antioxidant effects. Ascorbate in solution oxidizes rapidly. Transfected histamine receptor membrane suspension with protein concentration at >3.1 μg/ml (56 nM maximum histamine receptor) decreases the oxidation rate of 392 μM ascorbate, and virtually no ascorbate oxidation occurs at >0.0004 mol histamine receptor/mol ascorbate. Histamine receptor membrane had an initial ascorbate oxidation inhibition rate of 0.094 min·μg protein−1·ml−1, compared with rates for transfected ANG II membrane (0.055 min·μg protein−1·ml−1), untransfected membrane (0.052 min·μg protein−1·ml−1), creatine kinase (0.0082 min·μg protein−1·ml−1), keyhole limpet hemocyanin (0.00092 min·μg protein−1·ml−1), and osmotically lysed aortic rings (0.00057 min·μg wet weight−1·ml−1). Ascorbate enhancement of seven-transmembrane-spanning membrane receptor activity occurs in both adrenergic and histaminergic receptors. These receptors may play a significant role in maintaining extracellular ascorbate in a reduced state.

Cholesterol feeding impairs endothelium-dependent relaxation of rabbit aorta

1985 ◽  
Vol 63 (9) ◽  
pp. 1206-1209 ◽  
Author(s):  
R. L. Jayakody ◽  
M. P. J. Senaratne ◽  
A. B. R. Thomson ◽  
C. T. Kappagoda
Keyword(s):  
New Zealand ◽  
Thoracic Aorta ◽  
Rabbit Aorta ◽  
Cholesterol Diet ◽  
Cholesterol Feeding ◽  
New Zealand White Rabbits ◽  
Conventional Diet ◽  
Endothelium Dependent Relaxation

Experiments were designed to assess the effect of cholesterol feeding on the endothelium-mediated relaxation of the rabbit aorta to acetylcholine. Age-matched male New Zealand white rabbits were fed either a 2% cholesterol diet or standard rabbit chow. The animals were anaesthetized with sodium pentobarbitone and sacrificed after 4 and 8 weeks on these diets. Rings were prepared from the proximal thoracic aorta and examined in tissue baths. These rings were contracted first with norepinephrine (−6 log mol/L) and acetylcholine was added to demonstrate the endothelium-mediated relaxation. The endothelium-dependent relaxation was significantly less in aortas from rabbits fed the 2% cholesterol diet than in aortas from animals fed the conventional diet. This impairment of relaxation was apparent after both 4 and 8 weeks of cholesterol feeding. In both groups of animals no relaxation was seen in rings from which the endothelium was removed. These results show that cholesterol feeding leads to an impairment of endothelium-mediated relaxation of the rabbit aorta to acetylcholine.

scholarly journals Induction of Metalloproteinases by Glomerular Mesangial Cells Stimulated by Proteins of the Extracellular Matrix

2001 ◽  
Vol 12 (1) ◽  
pp. 88-96
Author(s):  
JOHN MARTIN ◽  
LISA EYNSTONE ◽  
MALCOLM DAVIES ◽  
ROBERT STEADMAN
Keyword(s):  
Mesangial Cells ◽  
Dynamic Equilibrium ◽  
Matrix Proteins ◽  
Dependent Manner ◽  
Glomerular Mesangial Cells ◽  
Matrix Components ◽  
Membrane Type ◽  
And Control ◽  
Dose Dependent ◽  
Synthesis And Degradation

Abstract. Human glomerular mesangial cells (HMC) are embedded in the mesangial matrix (MM) and control its turnover through a dynamic equilibrium between synthesis and degradation. Degradation is controlled by matrix metalloproteinases (MMP), whose activity has been causally implicated in the progression of glomerular disease. In other systems, MMP secretion may be directly affected by exposure to specific matrix proteins. The present study, therefore, investigated the effect of different matrix components on the adherence of HMC and on their secretion and activation of the gelatinases MMP2 and MMP9. HMC adhered strongly (quantified using crystal violet staining) to collagen IV and collagen I (P < 0.01, relative to binding to control, bovine serum albumin (BSA)-coated wells) and to a lesser extent to gelatin IV and fibronectin (P < 0.05). Binding to vitronectin and laminin was not statistically different to control wells. After the addition of these matrix proteins (0.1 μg/ml to 100 μg/ml) to growth-arrested HMC for 72 h, zymography of the conditioned medium established that only fibronectin and collagens I and IV dose-dependently increased latent (72 kD) MMP2 secretion and activation. Fibronectin, however, also induced the secretion of MMP9. Membranes from HMC that had been co-cultured with fibronectin for 72 h were prepared to investigate whether the activation of MMP2 in this system was due to the action of membrane-type (MT)-MMP. When incubated with latent MMP2 for times up to 24 h, these membranes activated the enzyme in a time- and dose-dependent manner. The results demonstrate that specific matrix components increased the secretion of MMP2 and MMP9 from HMC. In addition, MT-MMP activity, selectively induced by fibronectin, was implicated in the activation of the secreted proteinases.

Persistence of EDHF pathway and impairment of the nitric oxide pathway after chronic mercury chloride exposure in rats: Mechanisms of endothelial dysfunction

2010 ◽  
Vol 30 (11) ◽  
pp. 1777-1784 ◽  
Author(s):  
S Omanwar ◽  
K Ravi ◽  
M Fahim
Keyword(s):  
Nitric Oxide ◽  
Endothelial Dysfunction ◽  
Vascular Function ◽  
Rat Aorta ◽  
Mercury Exposure ◽  
Mercury Chloride ◽  
Dependent Manner ◽  
Selective Loss ◽  
Dose Dependent ◽  
Endothelium Dependent Relaxation

Chronic mercury exposure impairs vascular function, leading to the depression of endothelium-dependent vasodilatation. Loss of the nitric oxide (NO) pathway has been implicated, but little is known about effects on other endothelial mediators. This study investigated the mechanisms of endothelial dysfunction in rats subjected to chronic mercury chloride exposure. The endothelium-dependent relaxation of rat aorta evoked by acetylcholine (ACh) and isoproterenol was impaired in a dose-dependent manner by chronic mercury chloride exposure. Endothelium-independent responses to sodium nitroprusside (SNP) were not affected by chronic mercury chloride exposure. In healthy vessels, ACh-induced relaxation was inhibited by L-N-nitroarginine methyl ester (L-NAME; 10–4M) and partially by glybenclamide (10–5M), indicating the involvement of NO and endothelium-derived hyperpolarizing factor (EDHF). In vessels from mercury-exposed rats, responses to ACh were insensitive to L-NAME but were significantly reduced by glybenclamide, indicating selective loss of NO-mediated relaxation. In vessels from mercury-exposed rats, responses to ACh were partially restored after treatment with the antioxidant, superoxide dismutase (SOD) and catalase, this effect was not seen when aorta from exposed group was incubated with L-NAME along with SOD and catalase indicating selective loss of NO-mediated vasodilatation and with no affect the EDHF-mediated component of relaxation. The results imply that chronic mercury exposure selectively impairs the NO pathway as a consequence of oxidative stress, while EDHF is able to maintain endothelium-dependent relaxation at a reduced level.

Effects of topical corticosteroids on the sciatic nerve: an experimental study to adduce the safety in treating carpal tunnel syndrome

2011 ◽  
Vol 36 (3) ◽  
pp. 236-243 ◽  
Author(s):  
P.-H. Wang ◽  
C.-L. Tsai ◽  
J.-S. Lee ◽  
K.-C. Wu ◽  
K.-I. Cheng ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Evoked Potentials ◽  
Carpal Tunnel ◽  
Somatosensory Evoked Potentials ◽  
Corticosteroid Injection ◽  
Dependent Manner ◽  
Tunnel Syndrome ◽  
And Control ◽  
Dose Dependent ◽  
Mixed Nerve

Despite known detrimental effects on the blood flow and histology of nerves after intraneural corticosteroid injection, the neurotoxic effect of corticosteroids remains unclear. We investigated the effect of topical dexamethasone on nerve function. Two sponge strips soaked with dexamethasone at doses of 0.8, 1.6, and 3.2 mg were placed under and over the left sciatic nerve of adult Wistar rats for 30 minutes. Mixed-nerve-elicited somatosensory evoked potentials and dermatomal somatosensory evoked potentials were evaluated immediately and repeated together with functional tests and histology 2 weeks later. Evoked potential amplitude was dose-dependently lower and latency was prolonged in dexamethasone-treated sciatic nerves compared to controls. The suppression persisted with incomplete recovery for at least 4 hours, but differences between treated and control nerves were not significant after 2 weeks. Topical dexamethasone adversely affected neural conduction in a dose-dependent manner. Our results suggest that caution is required when using large doses of corticosteroid for injection of the carpal tunnel.

Sodium modulates inotropic response to hyperosmolarity in isolated working rat heart

1992 ◽  
Vol 263 (4) ◽  
pp. H1154-H1160 ◽  
Author(s):  
S. A. Ben-Haim ◽  
Y. Edoute ◽  
G. Hayam ◽  
O. S. Better
Keyword(s):  
Rat Heart ◽  
Control Period ◽  
Time Derivative ◽  
Left Ventricular ◽  
Dependent Manner ◽  
Bicarbonate Buffer ◽  
Dependent Behavior ◽  
Acute Changes ◽  
Dose Dependent ◽  
Working Rat Heart

The present study was designed to examine the effects of acute changes in perfusate Na+ concentrations and osmolarities on left ventricular (LV) mechanics in the isolated working rat heart model. Specifically, we separated the effect of isosmotic perfusates with different Na+ concentrations on LV mechanics. After a control period during which the hearts were perfused in a working mode with a control solution of Krebs-Henseleit bicarbonate buffer (Na+ of 136 meq/l, Ca2+ of 2.6 mM, and osmolarity of 300 mosM), the hearts were subjected to different perfusates (Na+ of 96-156 meq/l and osmolarity of 240-380 mosM, using different mannitol concentrations) in a semirandom order. Peak LV pressure (PLVP), maximal time derivative of LV pressure (dP/dtmax), and cardiac output (CO) were recorded. Increasing Na+ concentrations from 96 to 156 meq/l, using isosmotic perfusates, decreased PLVP, dP/dtmax, and CO in a dose-dependent manner. The dose-dependent behavior was evident for tonicities of 240, 280, 320, and 360 but not for 380 mosM. Increasing Na+ concentration from 96 to 136 meq/l at constant perfusate tonicity (320 mosM) decreased dP/dtmax from 6,753 +/- 133 to 5,602 +/- 418 mmHg/s (P < 0.001). Rearranging the same results to examine the effect of perfusate tonicity with iso-Na+ concentration demonstrated that increasing perfusate osmolarity had a dose-dependent effect on PLVP, dP/dtmax, and CO. At a constant Na+ concentration of 116 meq/l, increasing perfusate osmolarity from 240 to 320 mosM increased dP/dtmax from 6,116 +/- 132 to 7,274 +/- 594 mmHg/s (P < 0.01). Further increase in perfusate tonicity to 380 mosM decreased dP/dtmax to 2,338 +/- 398 mmHg/s (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Trypsinization of bovine parathyroid cells abolishes Ca2+-regulated parathyroid hormone secretion

1989 ◽  
Vol 122 (1) ◽  
pp. 213-218 ◽  
Author(s):  
R. Muff ◽  
J. A. Fischer
Keyword(s):  
Protein Kinase C ◽  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Adrenergic Receptors ◽  
Hormone Secretion ◽  
Dependent Manner ◽  
Kinase C ◽  
And Control ◽  
Β Adrenergic Receptors ◽  
Dose Dependent

ABSTRACT The secretion of parathyroid hormone (PTH) is inversely related to the extracellular Ca2+ concentration (Cae2+). To test the hypothesis that a Ca2+ sensor on the surface of parathyroid cells is involved in Ca2+-regulated PTH secretion, limited trypsinization of bovine parathyroid cells was carried out. Treatment with trypsin (1·1–10 mg/ml) inhibited, in a dose-dependent manner, PTH secretion stimulated by lowering Cae2+ from 2·0 to 0·5 mmol/l. In control cells, activation of protein kinase C with 12-O-tetradecanoylphorbol-13-acetate (TPA) enhanced PTH secretion at 2·0 mmol Cae2+/1 but not at 0·5 mmol Cae2+/1. In trypsinized cells, however, TPA enhanced PTH secretion at both 0·5 and 2·0 mmol Cae2+/1. Isoproterenol-stimulated PTH secretion was maintained in trypsinized cells, but reduced cyclic AMP production revealed that some β-adrenergic receptors were destroyed. The cytosolic free Ca2+ concentration (Cai2+), as measured with fura-2, was raised within seconds in response to increasing Cae2+ from 0·5 to 2·0 mmol/l and was then lowered within 1 min to a sustained plateau; the changes were the same in trypsinized and control cells. In conclusion, trypsinization of parathyroid cells abolished Ca2+-regulated PTH secretion without affecting Cai2+. Journal of Endocrinology (1989) 122, 213–218

scholarly journals Effects of Low-dose Electron Beam Irradiation on Respiration, Microbiology, Color, and Texture of Fresh-cut Cantaloupe

2005 ◽  
Vol 15 (4) ◽  
pp. 802-807 ◽  
Author(s):  
B.B. Boynton ◽  
C.A. Sims ◽  
M.O. Balaban ◽  
M.R. Marshall ◽  
B.A. Welt ◽  
...  
Keyword(s):  
Cucumis Melo ◽  
Modified Atmosphere Packaging ◽  
Life Extension ◽  
Plate Count ◽  
Modified Atmosphere ◽  
Dependent Manner ◽  
Total Plate Count ◽  
Fresh Cut ◽  
And Control ◽  
Dose Dependent

Cantaloupes (Cucumis melo) in three separate trials were cut into 1-inch cubes and irradiated at 0, 0.25, 0.5, 0.75, 1.0, 1.25, or 1.5 kGy; 0, 0.1, 0.2, 0.3, 0.4, 0.5, or 0.7 kGy; and 0, 0.3, 0.6, or 0.9 kGy, respectively. They were then stored in air at 3 °C for up to 20 days, and respiration rate, measured as carbon dioxide (CO2) production, microbiological counts [total plate count (TPC) and yeast and molds], texture, and color were measured during storage. Respiration rates were initially higher in irradiated cantaloupe. After 8 days, respiration was similar between irradiated and control fruit. Irradiation moderated increases in respiration in a dose-dependent manner. Highest irradiation doses resulted in initial TPC reductions of 1.5 log compared to the non-irradiated controls, and also prevented the 2.5 to 3 log TPC increases seen in controls after 10 to 11 days of storage. Texture differed on day 1, when controls were most firm, but irradiation maintained greater firmness than controls after day 7. Irradiation of fresh-cut cantaloupe has potential for shelf life extension and for integration with modified atmosphere packaging systems.

Sign in / Sign up

Export Citation Format

Share Document