Mechanisms of endothelial cell protection by curcumin in hypercholesterolemia.

Mechanism of curcumin for protection of endothelial cell was studied in cholesterolfed rabbits. Thirty rabbits were randomly divided into five groups. The negative control group was fed a standard diet, the positive control group was fed the same diet with 2 % cholesterol , the curcumin group was fed the same diet with 2 % cholesterol and curcumin 100 mg/Kg BW/day, 200 mg/Kg BW/day or 400 mg/Kg BW/day. The cholesterol-rich diet significantly increased Malondialdehyde (MDA) in the aortic blood vessels, as reflected by Thiobarbituric Acid-Reactive Substances (TBARS), inhibited endothelium-dependent vascular relaxations to acetylcholine and decrease cyclic GMP were compared with vessels from normal rabbits (negative control). In cholesterol-fed rabbits, curcumin treatment decreased MDA in plasma production, improved endothelium - dependent relaxations to acetylcholine and increase cyclic GMP production. These results suggest that dietary treatment of rabbits with curcumin may prevent superoxide anion (O2-) induced inactivation of endothelium-dependent relaxing factor (EDRF), improve the endothelium-dependent relaxation to acetylcholine in the aortic blood vessels and increase cyclic GMP content in aortic of cholesterol-fed rabbits.

Animal Experimental Study between the EDRF/NO And Endothelin in Regulative Relations / 医学研究杂志

Objective To probe into modulation effect between the EDRF/NO And ET.Methods In the whole Wister rat and rat's aorta perfusion model,they are carried through relative factors so that dynamic change of MABP,plasm ET-ir and cGMP level of tissue is observed.Results Whole Wister rat's experiment results:① In ET group,MABP first instantly(1~2min)reduces 6.58?0.67kPa,afterwards duratively enhances,it assumes the bidirectional response,when it reaches to 30min,MABP elevates 33.3?0.4kPa than before taking ET;Causes the aortic cGMP content to elevate,comparatively group control to increase 74.5%;② In L-NNA group,MABP slow rise,within 30min elevates to 4.62?2.04kPa;With control group comparison,the GMP level is reduced 5 times(0.42?0.08 versus the control 2.14?0.18pmol/mg Pr,P0.05);④ In Ach group,The vascular ET release reduces [406?31 versus control group 514?50pg/(g.w.w),P

Animal Experimental Study between the EDRF/NO And Angiotensin Ⅱ in Regulative Relations / 医学研究杂志

Objective To probe into modulation effect between the EDRF/NO And AngⅡ.Methods In the whole Wister rat and rat's aorta perfusion model,they are carried through relative factors so that dynamic changes of plasm AngⅡ-ir,cGMP level of tissue and vascular AngⅡ release level are observed.Results Whole Wister rat's experiment results:In AngⅡ group,the aortic cGMP content is markedly elevated compared with group control(P

Effect of Maturation on Endothelium-Dependent Relaxation in Pulmonary Arteries of the Newborn Rabbit

PURPOSE: This study was done to determine whether maturatin alters endothelium- dependent responses in pulmonary arteries. METHODS: Vascular rings of pulmonary arteries, with and without endothelium, taken from rabbits of 3 and 30 days of age were suspended in organ chambers filled with Krebs-Henseleit solution, bubbled with 95% O2-5% CO2 and maintained at 37degrees C. Immediately after mounting, the rings were stretched progressively until a maximal response to KCl was achieved. The rings were incubated with indomethacin and allowed to equilibrate before contraction and relaxation study. RESULTS: When the endothelium was intact in arterial rings from 3-day-old rabbits, acetylcholine (ACH) (10-6 M) relaxed preconstricted rings with histamine (5x10-6 M) (98.1 4.7% relaxation, mean SD). In rings without endothelium, KCl (10-2 to 9x10-2 M) and histamine (5x10-8 to 10-5 M) caused concentration-dependent contractions. When normalized to maximal contractions achieved to each agonist, the concentration-effect curves to KCl and histamine in rings without endothelium were similar to both ages. Rings with endothelium showed a progressive shift to the right of the concentration- effect curve to histamine. Relaxation to sodium nitroprusside were unaffected by age. In preconstricted ring, ACH (10-8 to 5x10-6 M) caused relaxations in rings with endothelium which were greater at 30-day compared to 3-day-old rabbits. CONCLUSION: These study demonstrates that endothelium-dependent relaxation increase with age, possibly due to changes in the release and/or effect of endothelium-derived relaxing factor (EDRF or nitric oxide) from pulmonary arteries during the neonatal period.

Comparison of the effects of EDRF on calcium-activated potassium channels of mesenteric artery smooth muscle between patients with essential hypertension and normotensive patients / 中国实用内科杂志

Objective To study the effects of Nitric oxide(NO),Nitric oxide synthases (NOS)on calcium-activated potassium channels (KCa) of mesenteric artery smooth muscle(SMC)between patients with essential hypertension (EH) and normotensive patients.Methods (1)Mesenteric artery branch from 21 EH and 18 normotensive patients respectively was digested by enzyme.Patch clamp technique was used to pull cell-attached and inside-out patches on mesenteric artery SMC from EH.The signal channel open number probability (Po),open dwell-time(To) and close dwell- time(Tc),were recorded.(2)The levels of plasma NO?NOS were measured by colorimetry analysis method.(3)The analysis of linear correlation was performed to estimate the relationship between the levels of plasma NO and Po?To?Tc of KCa of mesenteric artery SMC in the subjects of the two groups.Results (1)Compared to that of normotensive patients,the activities of KCa channels of patients with EH was higher.After adding Ca 2+ to cytoplasm,the Po of KCa channels in normotensive patients increased significantly.But there were few changes in EH group.(2)The levels of plasma NO?NOS were lower in EH group than in control group.(3)Linear correlation analysis showed that the levels of plasma NO were correlated positively with Po?To in normotensive patients,wherese the positive correlation were decreased in EH group.Conclusion The activities of KCa channels of patients with EH increase significantly.but the sensitivity to Ca 2+ decreased.NO?NOS may stimulate the KCa channels of normotensive and EH patients,but they may not be main factors in EH patients.

Mechanism of UV light-induced photorelaxation in isolated rat aorta

Isolated rat thoracic aorta which is pharmacologically precontracted by phenylephrine induces photorelaxation when exposed to long wave length UV-light. The aim of the present study was to characterize the mechanism of UV-light induced by photorelaxation in the rat aorta. 1. UV light relaxed both endothelium-intact and -denuded rat aortic rings contracted by phenylephrine. The magnitude of relaxation on UV light was dependent on the exposure time and slightly greatly in endothelium-denuded rings than in endothelium-intact preparations. 2. L-NAME (10 nM-100 uM) but not D-NAME completely inhibited the photorelaxation in a concentration dependent manner. 3. The UV-induced relaxation was inhibited by methylene blue (1 -100 uM), and verapamil (100 nM), and removal of extracellular Ca2+. In contrast, UV-light induced photorelaxation was potentiated by N(w)-nitro-Larginine (L-NOARG) treatment. 4. In immunocytochemical analysis of UV-light induced iNOS and eNOS expression in rat aortas, at which expression levels were increased in a time-dependent manner on UV-irradiation in aortic endothelium and smooth muscle, respectively. These results suggest that UV light-induced photorelaxation may be due to nitric oxide from exogenously administered L-arginine as well as endogenous nitric oxide donors such as amino acid and arginine derivatives. Additional suggestion is that UV light stimulates the expression of nitric oxide synthases, and its activity for nitric oxide generation is dependent on cytosolic Ca2+ originated from extracellular space.

Effects of Superoxide Dismutase on Changes in EDRF-and EDHF-Mediated Relaxation of Diabetic Rat Aortas Exposed to Oxygen Free Radicals / 대한내분비학회지

BACKGROUND: The relaxative response of blood vessels to acetylcholine (ACh) is known to be abnormal in diabetic rat due to changes in endothelium-derived relaxing factor (EDRF) and/or endothelium-derived hyperpolarizing factor (EDHF)-mediated action. Oxygen free radical (OFR) interferes with endothelium dependent relaxation to ACh in diabetic rats; this effect rnay be prevented by superoxide dismutase (SOD), OFR scavenger. Then, we determined the effect of SOD on modulation of OFR-induced damage to EDRF and EDHF-mediated relaxations to ACh in diabetic rat aortas. METHODS: After aortas were incubated with free radical generating system for 15 min with or without SOD pretreatment (150 U/mL) and contracted submaximally by norepinephrine (10 (-5) M), relaxative responses to cumulative concentrations (10 (-9) M to 10 (-5) M) of ACh were measured in aortas isolated from the control and 6-8 week streptozotocin-induced diabetic rat. We measured relaxative responses to ACh in these aortas treated with calmidazolium (100uM) or N-nitro-L-arginine methyl ester (luM) after exposure to OFR with/without SOD pretreatment, RESULTS: The ACh-induced relaxation (10 (-9)M to 10 (-5) M) was significantly decreased in diabetic than in control rat aortas (p<0.05). ACh-induced relaxation in diabetic rat aortas was significantly impaired from 79.3% to 71.2% after exposure to OFR (p<0.05), and the degree of ACh-induced relaxation was recovered from 71.2% to 84.0% after pretreatment with SOD (p<0.05). EDRF-mediated relaxation to ACh in diabetic rat aortas was significantly impaired from 71.2% to 61.6% after exposure to OFR (p<0.05), and the degree of impairment of ACh-induced EDRF-mediated relaxation was recovered from 61.6% to 76.0% after pretreatment with SOD. After exposure to OFR, EDHF-mediated relaxation to ACh in diabetic rat aortas was not significanlty impaired. However, the degree of impairment of EDHF-mediated relaxation to ACh was recovered from 46.0% to 59.5% after pretreatment with SOD. CONCLUSION: This study suggests that OFR may impair mainly EDRF-mediated relaxation to ACh and SOD may protect rnainly OFR-induced damage to EDRF-mediated relaxation to ACh in diabetic rat aortas.

The action of Halothane and Isoflurane in Aortic Rings of Rabbit Pretreated with LNAME (L-nitrow arginine methyl ester) and MB (methylene blue) / 대한마취과학회지

BACKGROUND: The action of the volatile anesthetics on various organs in the body is not well known. Since Furchgott (1980) discovered endothelium derived relaxing factor (EDRF) from endothelium, many studies have been tried. Many investigators were studied about the relationship between the EDRF and the effect of the volatile anesthetics on blood vessels too. But the effect of volatile anesthetics and the site of action on the blood vessel were still controversial. In this study, we evaluated that the effect and the action site of halothane and isoflurane on isolated aortic rings of the rabbit. METHODS: Each of obtained thoracic aorta from rabbits (1.5~2.5 Kg) was divided into 3~5 mm sized rings, and a half of that were denuded. All of the aortic rings were preconstricted with phenylephrine 1.5 10-7 Mole in warm organ bath filled with modified Krebs' solution, and then LNAME (inhibitor of nitric oxide synthase, 3 10-4Mole) was administered to one group of aortic rings. MB (inhibitor of soluble guanylate cyclase, 2 10-5Mole) was administered to another one group and neither of LNAME nor MB was administered to the other group. And then isoflurane or halothane was administered (1~4%) to all of aortic rings. The polygraph recorded the changes of tension of aortic ring which was transmitted through the force transducer. RESULTS: It was proved that basal EDRF was released from endothelium by the fact that intact aortic rings were more constricted after LNAME or MB administration. The intact aortic rings were constricted in all concentration of isoflurane and both intact and denuded rings were relaxed in 4% concentration of halothane. CONCLUSION: It is concluded that isoflurane in all concentrations has an endothelium -mediated vasoconstriction and 4% halothane produced vascular relaxation directly independent of existence of the endothelium of vessel.

The Effect of Nitric Oxide on Cat Corpus Cavernosum Relaxation Under Hypoxia (In vivo Study) / 대한비뇨기과학회지

One of the pathophysiologic change of priapism is known as hypoxic condition of corpus cavernosum. In vitro study of corpus cavernosum under hypoxia showed suppressed endothelium- dependent relaxation caused by cholinergic and nonadrenergic noncholinergic neuroeffector system, but in vivo study it is not fully evaluated yet. So this study aimed to identify the changes of corpus cavernosum related to cholinergic neuroeffector system and endothelium derived relaxation factor (EDRF) under hypoxia in animal study and to understand the Physiologic change of priapism. Under the general anesthesia with tracheostomy, adult male cats were conditioned at normoxia and hypoxia with ventilation. Acetylcholine, Nc-monomethyl-L- arginine (L-NMMA) and L-arginine was infused via internal pudendal artery. The change of intracavernosal pressure in response to drugs were monitored with physiograph (Gilson, IC-MP) in both normoxic and hypoxic state. The relaxation effect of acetylcholine under hypoxia was weaker than under normoxia (n=5, p suppressed by L-NMMA under normoxia but not under hypoxia. L-arginine showed the relaxation effect under normoxia but, no relaxation under hypoxia. These result suggest that acetylcholine induced relaxation was influenced in a some by hypoxic condition but not suppressed completely. EDRF pathway via nitric oxide synthesis does not play a role in relaxation of cat corpus cavernosum under hypoxia.

Role of Endothelium-derived Relaxing and Hyperpolarizing Factors in the Relaxation of the Corpus Cavernosum / 대한비뇨기과학회지

It has been found that acetylcholine releases at least two different substances from the vascular endothelial cells, i.e., relaxing factor and hyperpolarizing factor. The present study was armed to investigate whether and to what extent these factors are involved in the relaxation of the corpus cavernosum. The corpus cavernosum was isolated from male New Zealand white rabbits and suspended longitudinally in an organ bath. The corporal strips were precontracted with phenylephrine, tetraethylammonium (TEA) or potassium chloride, and their responses to electrical field stimulation (EFS) or exogenously-administered acetylcholine were examined. EFS caused a frequency-dependent relaxation of the corpus cavernosum precontracted with phenylephrine, which was significantly inhibited or abolished in the presence of procaine (3.5 x 0.0001mol/L) or ouabain (0.0001mol/L). The corporal preparation precontracted with TEA also showed a frequency-dependent relaxation, however, the degree of which was lower than that precontracted with phenylephrine. EFS was without a significant effect on the corporal preparation precontracted with KCl (3 x 0.01mol/L). Acethylcholine elicted a concentration-dependent relaxation of the corpus cavernosum, the magnitude of which was significantly diminished in the presence of L-NAME (0.0001 mol/L). The relaxation response to EFS of the corporal preparation precontracted with phenylephrine was significantly attenuated in the presence of L-NAME (0.0001 mol/L), in which the residual relaxation was completely abolished by glibenclamide (0.00001mol/L). The relaxation of the corpus cavernosum in response to EFS was reversed into a contraction by methylene blue (0.0001mol/L) or TEA (0.01mol/L). These results suggest that endothelium-derived relaxing and hyperpolarizing factors released upon neural stimulation mediate the relaxation of the corpus cavernosum. It is also suggested that EDRF activates soluble guanylate cyclase and EDHF does ATP-sensitive potassium channels.

A Study of Endothelium-dependent Pulmonary Arterial Relaxation and the Role of Nitric oxide on Acute Hypoxic Pulmonary Vasoconstriction in Rats / 결핵

BACKGROUND: Since the demonstration of the fact that vascular relaxation by acetylcholine(Ach) results from the release of relaxing factor from the endothelium, the identity and physiology of this endothelium-derived relaxing factor(EDRF) has been the target for many researches. EDRF has been identified as nitric oxide(NO). With the recent evidences that EDRF is an important mediator of vascular tone, there have been increasing interests in defining the role of the EDRF as a potential mediator of hypoxic pulmonary vasoconstriction. But the role of EDRF in modulating the pulmonary circulation is not compeletely clarified. To investigate the endotbelium-dependent pulmonary vasodilation and the role of EDRF during hypoxic pulmonary vasoconstriction, we studied the effects of N(G)-monornethyl-L-arginine(L-NMMA) and L-arginine on the precontracted pulmonary arterial rings of the rat in normoxia and hypoxia. METHODS: The pulmonary arteries of male Sprague Dawley(300~350g) were dissected free of surrounding tissue, and cut into rings. Rings were mounted over fine rigid wires, in organ chambers filled with 20ml of Krebs solution bubbled with 95 percent oxygen and 5 percent carbon dioxide and maintained at 37℃. Changes in isometric tension were recorded with a force transducer(FT. 03 Grass, Quincy, USA). RESULTS: 1) Precontraction of rat pulmonry artery with intact endothelium by phenylephrine(PE, 10(-6)M) was relaxed completely by acetylcholine(Ach, 10(-9) -10(-5)M) and sodium nitroprusside (SN, 10(-9) -10(-5)M), but relaxing response by Ach in rat pulmonary artery with denuded endothelium was significantly decreased. 2) L-NMMA(10-4M) pretreatment inhibited Ach(10(-9) -10(-5)M)-induced relaxation, but L-NMMA(10-4M) had no effect on relaxation induced by SN(10(-9) -10(-5)M). 3) Pretreatment of the L-arginine(10(-4)M) significantly reversed the inhibition of the Ach(10(-9) -10(-5)M)-induced relaxation caused by L-NMMA(10(-4)M). 4) Pulmonary arterial contraction by PE(10(-6)M) was stronger in hypoxia than normoxia but relaxing response by Ach(10(-9) -10(-5)M) was decreased. 5) With pretreatment of L-arginine(10(-4)M), pulmonary arterial relaxation by Ach(10(-9) -10(-5)M) in hypoxia was reversed to the level of relaxation in normoxia. CONCLUSION: It is concluded that rat pulmonary arterial relaxation by Ach is dependent on the intact endothelium and is largely mediated by NO. Acute hypoxic pulmonary vasoconstriction is related to the suppression on NO formation in the vascular endothelium.

Effects of Volatile Anesthetics on Isolated Rings of Thoracic Aorta in Rats / 대한마취과학회지

Halothane, enflurane, and isoflurane are generally regarded as vasodilators. This property has been attributed to a direct action on vascular smooth muscle or the inhibition of vasoconstricition by endogenous neurohumoral substances. Because of the importance of the endothelium in determining of modulating the vascular responses of a wide vareity of agents, vascular effects of halothane, enflurane and isoflaurane on isolated rings of thoracic aorta in Sprague-Dawley rats were studied in the presence and absence of intact endothelium. Halothane, enflurane and isoflurane induced relaxation on thoraeic aortic rings precan-tracted with 50mM KCl both with and without endothelium. Halothane also induced vasodilation in both aortic rings precontracted with 10-6 M phenylephrine. And enflurane and isoflurane induced vasodilation in denuded aortic rings precontracted with phenylephrine. But endothelium intact rings demonstrsted significant(p<0.05) vasoconstriction at low concentrations of both enflurane and isoflurane followed by vasodilation at higher concentra- tion precontracted with phenyephrine. These results suggest that at low concentration and intact rings, enflurane and isoflurane eause vasoconstriction through inhibition of basal EDRF production and /or stimulation of the release of an endothelium derived constricting factor. At higher concentration, a direct vasodilating effect of the anesthetic predominance.

Phorbol Ester Modulates th Action of Acetylcholine in Rabbit Carotid Artery

Authors studied the regulatory mechanism of protein kinase C on the action of acetylcholine in rabbit carotid artery. The arterial rings were myographied isometrically in an isolated organ bath. In this study, acetylcholine relaxed phenylephrine-induced contraction of rabbit carotid artery in the presence of endothelium. In the pretreatment of methylene blue or nitro-L-arginine, the action of acetylchioline was reduced. Pretreatment of phorbol 12-myristate 13-acetate(PMA) attenuated the action of acetylcholine, but PMA did not attenuated it in the presence of staurosporine, suggesting that protein kinase C suppressed the action of acetylcholine. The potency of phorbol ester on the action of acetylcholine was PMA>phorbol 12, 13-dibutyrate(PDBu)>phorbol 12,13-diacetate(PDA), but the direct effect of phorbol on the contraction of arterial rings was PDBu>PMA>PDA. This implied that protein kinase C involved in the contraction of smooth muscle and the attenuation of the action of acetylcholine were different. PMA did not affect on A23187- and sodium nitroprusside-induced vasorelaxation. Acetylcholine increased tissue cGMP contents, which was reduced by PMA. These results suggest that in rabbit carotid artery protein kinase C reduce acetylcholine-stimuated endothelium derived relaxing factor(EDRF) release by affecting membrane receptor, and do not affect on the function of EDRF and cGMP production in the smooth muscle.

Effects of Vanadate on the Contractility of Vascular Smooth Muscle

Vanadate is a trace element in animal tissues and has been known to inhibit NA(+)-K(+) ATPase in various tissues including skeletal and cardiac muscles and smooth muscles. Vanadate shows contractile actions on various types of smooth muscles. Prolonged dietary administration of vanadate has been shown to cause arterial hypertension, increased peripheral resistance, and a marked reduction of coronary, visceral and renal blood flow.In isolated vascular smooth muscle of aorta, application of vanadate caused contraction. These studies have been conducted the preparation of vascular smooth muscles from which endothelial cell were removed. It has been reported that endothelial cell releases relaxing factor(s) (endothelium-derived relaxing factor, EDRF) in response to acetylcholine and a number of other stimuli and also produces vasoconstrictor substances (endothelium-derived contracting factor, EDCF). The aim of this present experiment is to elucidate whether vascular response of isolated rabbit aorta induced by vanadate are endothelium dependent or not. The result obtained were summarized as follows ; 1) When endothelium was intact, vanadate induced vascular relaxation of aorta precontracted with norepinephrine. But K+ induced contraction was augmented by vanadate in the aorta with or without endothelium. Whereas relaxation produced by vanadate precontracted with angiotensin II was endothelium-independent. 2) Hemoglobin, methylene blue, hydroquinone, and verapamil inhibited vanadate-induced vascular relaxation. But indomethacin and quinacrine had no effect on vanadate induced vascular relaxation. From the above results, it is speculated the vanadate act on endothelium, modifies the synthesis or release of endothelium-dependent relaxing factor and thus changes the contractile responses to norepinephrine in rabbit aorta.

Role of Endothelium -Derived Relaxing Factor in the Pathogenesis of Coronary Artery Spasm and Its Relationship with Ethanol

Isometric tension recording was performed in the transverse strips of porcine coronary arteries and rabbit aorta to observe the effects of the endothelium and endothelium-derived relaxing factor(EDRF) on vasomotor tone and to test the hypothesis that alcohol may have the deleterious effect on endothelium-dependent vasorelaxation. Tension-development by vasoconstrictor was markedly attenuated in the endothelium-intact strips compared to the endothelium denuded strips. Administration of hemoglobin(10-5M) to inhibit the action of EDRF increased tension selectively in the endothelium-infarct strips, which is suggestive of basal EDRF secretion. Nitro L-arginine(10-5M). an analogue of L-arginine(10-4M) partially reversed the inhibitory effect of nitro L-arginine. Ethyl alchol inhibited bradykinin-induced endothelium-dependent vasorelaxation of porcine coronary artery in dose dependent manner. These data suggest that the protective effect of vascular endothelium to the action of vasoconstirctor can be explained by exercise of basal EDRF release and damaged endothelium would be a great risk of induction of vasospasm. Also we believe that there is a relationship of competive inhibition between L-arginine. a precursor of EDRF, and its analogues on the action of EDRF and alcohol intake would be hazardous to the patients with coronary artey disease because its inhibitory action on endothelium-dependent vasorelaxation may evoke myocardial ischemia.

Contractile and Inhibitory Effects of McN-A-343 and Acetylcholine on Isolated Arteries

Effect of acetylcholine(ACh) and McN-A-343 on porcine coronary artery and rabbit thoracic aorta were investigated in isolated preparations with or without intact endothelium. In the porcine coronary artery, ACh produced concentration dependent contraction which was greater in rings without the endothelium than in intact endothelial rings, but McN-A-343 did not alter the basel tension in both tissues. ACh relaxed contraction induced by 5-hydroxytryptamine(5-HT) in only intact endothelial rings, while NcN-A-343 inhibited the 5-HT induced tension in both preparations dose dependently. Carbachol elicited a prominent contraction in both tissues. The carbacol-induced tension was markedly inhibited by McN-A-343 in either rings with or without endothelium, while ACh contracted further the tension. ACh and McN-A-343 did not after the KCi induced tension, but clearly potentiated the contraction induced by Bay K 8644 in intact endothelial rings. In rabbit thoracic aorta, ACh elicited contraction in a concentration-dependent fashion which was potentiated by removal of endothelium, but McN-A-343 did not affect the basal tension of both rings. ACh inhibited the 5-HT-induced contraction in only intact endothelial ring, but McN-A-343 did not change the contraction of both rings. Conclusively, ACh produces endothelium-dependent relaxation in both arteries, while McN-A-343 elevated endothelium-independent inhibition to 5-HT or carbachol-induced tension.