Propentofylline and postischemic brain edema: Relation to Na+-K+-ATPase activity

Following the bilateral occlusion of common carotid arteries in gerbil, an increase in water content and sodium/potassium ratio as well as the inhibition of Na⁺-K⁺-ATPase was found. The xanthine derivative propentofylline (HWA 285) [3-methyl-1-(5-oxohexyl)-7-propylxanthine] given either before or after cerebral ischemia attenuated the development or postischemic brain swelling and the increase in sodium/potassium ratio and prevented the postischemic reduction of Na⁺-K⁺-ATPase activity. It is concluded that the action of propentofylline on brain edema during ischemia is mediated aside from other possible mechanism(s), by the influence of the drug on Na⁺-K⁺-ATPase activity.     

缺血预处理减轻心肌缺血再灌注诱导的Na+-K+-ATP酶异常表达

目的：探讨Na^＋ -K^＋ -ATP酶在心肌缺血预处理保护机制中的作用。方法：以前降支结扎30min后复灌60min制备心肌缺血再灌注模型，连续3次缺血5min再灌注10min制备缺血预处理模型。以毛花甙丙抑制Na^＋ -K^＋ -ATP酶功能，观察心脏收缩和舒张功能、心肌Na^＋ -K^＋ -ATP酶功能，免疫组化法检测Na^＋ -K^＋ -ATPα1、α2、α3及β1亚基的蛋白表达。结果：心肌缺血再灌注显著抑制心脏舒缩功能、Na^＋ -K^＋ -ATP酶活性以及α1、α2、α3及β1亚基的蛋白原位表达；缺血预处理可减轻心肌缺血再灌注诱导的Na^＋ -K^＋ -ATP酶异常，保护心脏功能；毛花甙丙可维持心脏舒缩功能，但显著抑制Na^＋ -K^＋ -ATP酶和蛋白表达。结论：缺血预处理能减轻心肌缺血再灌注诱导的Na^＋ -K^＋ -ATP酶异常，抑制Na^＋ -K^＋ -ATP酶功能导致缺血预处理保护作用丧失，维持Na^＋ -K^＋ -ATP酶功能是缺血预处理心肌保护重要机制之一。     

Inhibition of rat brain Na+-K+-ATPase by triterpene glycosides from holothurians

The effect of triterpene glycosides from holothurians on Na+-K+-ATPase of rat brain was investigated. The marine glycosides are irreversible inhibitors of the enzyme with an average I50 value of 10(-4) M. ATP had a low protective effect against inhibition. The inhibitory effect was increased by preincubation with MgCl2. There was alteration of the activation curve of Na+-K+-ATPase by NaCl and KCl in the presence of glycosides. Triterpene glycosides inhibited the K+-phosphatase activity, but to a smaller degree than the ATPase activity. Na+-K+-ATPase of pig kidney was less sensitive to the marine triterpene glycosides than the brain enzyme. The marine glycosides did not alter the specific binding of [3H]-ouabain to the Na+-K+-ATPase.     

Reduced hyperpolarization of endothelial cells following high dietary Na+: effects of enalapril and tempol

1. High dietary Na(+) is associated with impaired vascular endothelial function. However, the underlying mechanisms are not completely understood. In the present study, we investigated whether the endothelial hyperpolarization response to acetylcholine (ACh) exhibited any abnormalities in Wistar rats fed a high-salt diet (HSD) for 1 month and, if so, whether chronic treatment with the angiotensin-converting enzyme inhibitor enalapril or the anti-oxidant tempol could normalize the response. Membrane potential was recorded using the perforated patch-clamp technique on the endothelium of rat aorta. 2. Acetylcholine (2 μmol/L) produced a hyperpolarization sensitive to TRAM-34, a blocker of intermediate-conductance Ca(2+) -sensitive K(+) channels (IK(Ca)), but not to apamin, a blocker of small-conductance Ca(2+)-sensitive K(+) channels (SK(Ca)). NS309 (3 μmol/L), an activator of SK(Ca) and IK(Ca) channels, produced a hyperpolarization of similar magnitude as ACh. 3. In the HSD group, the ACh-evoked hyperpolarization was significantly attenuated compared with that in the control group, which was fed normal chow rather than an HSD. Similarly, the hyperpolarization produced by NS309 was weaker in tissues from HSD-fed rats. 4. Combination of HSD with chronic enalapril treatment (20 mg/kg per day for 1 month) normalized endothelial hyperpolarizing responses to ACh. Chronic tempol treatment (1 mmol/L in tap water for 1 month) prevented the reduced hyperpolarization to ACh. 5. The results of the present study indicate that excess in dietary Na(+) results in a failure of endothelial cells to generate normal IK(Ca) channel-mediated hyperpolarizing responses. Our observations implicate oxidative stress mediated by increased angiotensin II signalling as a mechanism underlying altered endothelial hyperpolarization during dietary salt loading.     

Na+/Ca2+ exchanger inhibitor ameliorates impaired endothelium-dependent Na+ relaxation induced by high glucose in rat aorta

The present study was designed to investigate the effects of KB-R7943, an inhibitor of the Na+/Ca2+ exchanger, on impaired endothelium-dependent relaxation (EDR) induced by high glucose in rat isolated aorta. Both acetylcholine (ACh)-induced EDR and sodium nitroprusside (SNP)-induced endothelium-independent relaxation (EIR) were measured after aortic rings had been exposed to high glucose in the absence and presence of KB-R7943. Coincubation of aortic rings with high glucose (25 mmol/L) for 24 h resulted in a significant inhibition of EDR, but had no effect on EIR. After incubation of aortic rings in the presence of both KB-R7943 (0.1-10 micromol/L) and high glucose for 24 h, significantly attenuation of impaired EDR was observed. This protective effect of KB-R7943 (10 micromol/L) was abolished by superoxide dismutase (SOD; 200 U/mL) and l-arginine (3 mmol/L), whereas d-arginine (3 mmol/L) had no effect. Similarly, high glucose decreased SOD activity and the release of nitric oxide (NO) and increased superoxide anion (O2(-)) production in aortic tissue. KB-R7943 significantly decreased O2(-) production and increased SOD activity and NO release. These results suggest that KB-R7943 can restore impaired EDR induced by high glucose in rat isolated aorta, which may be related to the scavenging of oxygen free radicals and enhanced NO production.     

复合离子盐对老年人细胞内Na+、K+、Ca2+的影响及其机制

目的：观察复合离子盐对老年人细胞内Na^＋、K^＋、Ca^2＋及红细胞膜钠泵和钙泵活性的影响。方法：在天津市河东区社区中抽取226例老年人作为研究对象．其中高血压者112例。正常血压者114例。两者再随机分为离子盐组和普通加碘盐组．分别给予复合离子盐和普通加碘盐摄入，6个月后观察研究对象细胞内Na^＋、K^＋、Ca^2＋及钠泵、钙泵活性的变化。结果：6个月时高血压患者中离子盐组细胞内钠、钙离子浓度低于基线水平（P〈0．05），但钾离子无明显变化。离子盐组钠泵、钙泵活性均明显高于基线水平（P〈0．05），但在正常血压者中，2组与基线水平比较差异无统计学意义。结论：复合离子盐可增强钠泵、钙泵活性，使细胞内的钠、钙含量减少。     

大鼠主动脉内皮细胞原代培养的研究

目的建立简单有效且重复性高的大鼠主动脉血管内皮细胞体外原代培养技术。方法取大鼠主动脉,将主动脉内膜暴露于外,采用不同浓度的Ⅰ型胶原酶以及不同消化时间对组织块进行预消化,然后将大鼠主动脉切成小块按内膜朝下贴在鼠尾胶原包被的培养瓶上进行培养。结果2.0g·L-1型胶原酶消化1h的组织块细胞迁出速度且组织迁出率明显提高(P<0.05),组织贴壁后24h即可见内皮细胞从组织块周围游离出来,呈短梭形或类三角形,d4～5即可进行传代培养,传代后d3～4即可融合成单层,呈典型“铺路石”状排列,经免疫组化S-P法鉴定有第Ⅷ因子相关抗原存在,进一步确认其为内皮细胞。结论经2.0g·L-1Ⅰ型胶原酶消化1h的组织块,组织块迁出率及内皮细胞迁出速度明显提高,从而大大缩短原代培养的时间。     

Role of the endothelium in the vasodilator response of rat thoracic aorta to histamine

Despite their potent vasodilating action in vivo, acetylcholine and histamine often show a vasoconstricting action in vitro. As the endothelium has an important role in the vasodilating effect of acetylcholine, we investigated the possible role of the endothelium in the vasodilating effect of histamine in comparison to acetylcholine. Experiments were done on ring segments of rat thoracic aorta mounted for isometric tension measurements. We demonstrated that relaxation by histamine and acetylcholamine of pre-contracted rat aorta segments required the presence of endothelial cells. Acetylcholine acting on muscarinic receptors, and histamine acting on H₁-receptors seemed to initiate the production of mediator(s) from the endothelial cells, which leads to relaxation of the vascular smooth muscle cells. This production appeared to be depressed by ETYA and hydroquinone, and under hypoxic conditions.     

Physicochemical characteristics of interaction of toxic triterpene glycosides from holothurians with rat brain Na+-K+-ATPase

High-angle X-ray diffraction spectra showed that triterpene glycosides form crystalline complexes with membrane cholesterol. Electron microscopy demonstrated a decreased vesicle size, of the membrane preparation from rat brain which is enriched in Na+-K+-ATPase, by the triterpene glycosides. The Arrhenius plot was linear in the presence of triterpene glycosides. The half-width of the phosphatidylcholine N-methyl proton line in proton NMR spectra was not altered in the presence of marine glycosides. The excimer formation of pyrene, a hydrophobic fluorescent probe, was significantly decreased by triterpene glycosides. The increase of tryptophanyl residue fluorescence demonstrated a change of the Na+-K+-ATPase conformation after treatment with cytotoxic glycosides.     

Na+ -K+ -2Cl- cotransporter is implicated in gender differences in the response of the rat aorta to phenylephrine

Inhibition of the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) with bumetanide reduced contractile responses to phenylephrine (PE) in male rat aortas (129+/-4% of 60 mM KCl-induced contraction control vs 108+/-7% bumetanide; PE 10(-5) M; P<0.01) but did not change equivalent responses in female rat aortas. Removal of the endothelium blunted the effect of NKCC1 inhibition on the response to PE (10(-5) M) in males, whereas in denuded aorta from female rats, bumetanide reduced this response (162+/-5% control vs 146+/-3% bumetanide; P<0.05). NKCC1 basal activity did not show gender differences in intact aortic rings, but in the presence of PE, bumetanide-sensitive (86)Rb(+)/K(+) uptake increased more in male than female aortas (179+/-8 in males vs 158+/-5 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1) in females; P<0.05). PE did not stimulate NKCC1 activity in denuded aorta from male rats. However, in female rats, PE increased NKCC1 activity similarly in both denuded (169+/-11 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1)) and intact aortas. Ovariectomy increased the bumetanide-sensitive (86)Rb(+)/K(+) uptake increase elicited by PE (223+/-17 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1)) and hormone replacement with 17beta-estradiol prevented this effect (159+/-29 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1)). Na(+),K(+)-ATPase basal activity, measured as ouabain-sensitive (86)Rb(+)/K(+) uptake, was similar in male and female rats, but the effect of PE was significantly less in intact male aortas (232+/-16 in males vs 296+/-25 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1) in females; P<0.05). Our results suggest that PE induced activation of NKCC1 and Na(+),K(+)-ATPase in the rat aorta in a gender-dependent way.     

灯盏花素在大鼠糖尿病早期对近球小管钠钾ATP酶活性的影响

目的观察灯盏花素(Bre)在大鼠糖尿病早期对近球小管(PT)钠钾ATP酶(Na+,K+-ATPase)活性的影响以及对肾脏的保护作用。方法实验分为模型组(DM组)、灯盏花素治疗组(Bre组)和正常对照组(NC组)。前两组以链脲佐菌素(STZ,65mg·kg-1)腹腔注射建立糖尿病大鼠模型。Bre组在模型建立成功后连续4wk予腹腔注射灯盏花素20mg·kg-1.d-1,NC组和DM组则在相同的时间腹腔注射同体积的生理盐水。4wk后动物在麻醉下行双侧输尿管插管,收集尿样并行心脏穿刺取血;对一侧肾动脉进行灌注后,取肾皮质组织孵育,在显微镜下手工分离单根PT,用液闪法检测其Na+,K+-ATPase活性。检测血糖及血、尿的肌酐水平,放免法测定尿微量白蛋白、尿β2-微球蛋白(β2-MG)及血清内源性洋地黄样物质(EDLS)水平。结果NC组PT的Na+,K+-ATPase活性为(959.11±117.35)pmolPi·mm-1·h-1,DM组则明显增高达(1893.53±383.90)pmolPi·mm-1·h-1(P<0.01),Bre组为(1262.09±125.14)pmol Pi·mm-1·h-1,虽然高于NC组(P<0.05),但却明显低于DM组(P<0.05)。DM组的血清EDLS水平明显低于NC组(P<0.01),Bre组的血清EDLS水平虽然也低于NC组(P<0.05),但却高于DM组(P<0.01)。分别与NC组和DM组比较,Bre组的血糖水平明显高于NC组,而与DM组差异无显著性,除此之外,其尿量、尿β2-MG、尿白蛋白排泄率(UAER)和肌酐清除率(Ccr)都与DM组有相同性质的变化,但变化幅度都小于DM组(P<0.05)。结论Bre在大鼠糖尿病早期对肾小管Na+,K+-ATPase活性增强有限制作用,此作用的机制可能与Bre在此期间限制了EDLS释放减少的程度有关;在相同的实验条件下,Bre对大鼠糖尿病早期肾脏具有保护作用。     

Effects of monovalent cations on (Na+ + K+)-ATPase in rat brain slices.

The influence of monovalent cations on membrane (Na + K+)-ATPase was estimated in vitro in intact cells from the oxygen consumption of rat brain cortical slices. High concentrations of K+, Rb+ or Cs+ stimulated the respiration in the presence of Na+. This stimulation was antagonized by ouabain in a concentration- and time-dependent manner. Additionally, only combinations of monovalent cations, that stimulate (Na+ + K+)-ATPase, increased oxygen consumption, indicating that the stimulated portion of respiration is realted to the (Na+ + K+)-ATPase activity. Low concentrations of Rb+ and Cs+, however, failed to affect oxygen consumption. Li+ slightly and transiently stimulated oxygen uptake at low concentrations and inhibited it at higher concentrations. Low concentrations of Tl+ also stimulated respiration in a K+-free medium. However, the inhibitory effects of Tl+ were predominant at higher concentrations or in the presence of K+. Thus, monovalent cations can alter (Na+ + K+)-ATPase activity. While Rb+ and Li+ produce opposite effects on this enzyme system under certain conditions, these actions do not seem to be related to the antidepressant action of Rb+ and the antimanic action of Li+.     

Cholinergic regulation of Na+-K+-ATPase activity in rat parotid gland: changes after castration

In this study, we investigated the different signalling pathways involved in muscarinic acetylcholine M(3) receptor-dependent modulation of Na(+)-K(+)-ATPase in parotid glands from normal and castrated rats. Carbachol inhibited the enzyme activity in parotid glands from control rats while it stimulated the enzyme activity in castrated rats. The inhibition of Ca(2+) calmodulin by trifluoperazine abolished the inhibitory effect of carbachol in control rats, while the inhibition of protein kinase C by staurosporine stimulated Na(+)-K(+)-ATPase. In castrated rats, trifluoperazine inhibited the carbachol-stimulant effect while staurosporine had no effect. Results indicate that in control glands the activation of a phospholipid-Ca(2+) calmodulin-dependent protein kinase C is responsible for the inhibitory effect of carbachol on Na(+)-K(+)-ATPase activity. In castrated rats, the activation of the enzyme by carbachol is regulated by its Ca(2+) calmodulin-stimulating action, and not by activation of protein kinase C. The activation of the Na(+)-K(+)-ATPase observed in castrated rats resulted in a decrease in carbachol-induced net K(+) efflux and thereby could decrease salivary fluid production.     

Evidence for a common defect associated with pressure in the aorta of two hypertensive rat strains

1. Thoracic aortas of normotensive (Wistar-Kyoto (WKY) and Lyon normotensive (LN)) and hypertensive (spontaneously hypertensive rats (SHR) and Lyon hypertensive (LH)) rats from two groups (Japanese (WKY rats and SHR) and Lyon (LN and LH rats)) were compared using organ chambers. Changes in endothelium and smooth muscle reactivity to noradrenaline (NA), carbamylcholine and N omega-nitro-L-arginine (L-NNA) were analysed to distinguish between changes in reactivity that are associated with the presence of hypertension and those that are dependent on group (Japanese vs Lyon). 2. Aortas of hypertensive rats had lower pD2 values for NA than aortas from normotensive rats. These differences were associated with hypertension (P < 0.005 and P < 0.01) and group (P < 0.005 and P < 0.005) in presence or absence of endothelium, respectively, whereas no difference was seen in the maximal developed tension in response to NA. 3. Aortas also differed by a reduced ability to relax in response to carbamylcholine in hypertensive rats; this effect is hypertension (P < 0.05) and group (P < 0.005) dependent, without any change in carbamylcholine pD2 values. 4. Changes in maximum developed tension in the presence of L-NNA were found to be endothelium dependent and pressure and group independent. Furthermore, the change in tension induced by L-NNA appears significantly more pronounced in SHR than in LH rats (P < 0.05). 5. These results indicate that the common defect associated with hypertension appears to be linked to the endothelium through alpha-adrenoceptors and muscarinic receptors in both the Japanese and Lyon groups. However, SHR differs markedly from LH rats by having a higher developed tension in response to NA, this increased tension being counterbalanced by the release of nitric oxide, as observed in the presence of L-NNA.     

PbCl2-induced hyperpolarization of rat thymocytes: involvement of charybdotoxin-sensitive K+ channels

The effect of PbCl2 on membrane potential and intracellular divalent metal cation concentrations of rat thymocytes was examined by flow cytometry. PbCl2 at concentrations of 0.3 microM or higher (up to 10 microM) produced persistent, dose-dependent hyperpolarization (decrease in the intensity of di-BA-C4 fluorescence). Removal of external Ca2+ did not significantly affect the PbCl2-induced hyperpolarization. Charybdotoxin, a specific antagonist of Ca(2+)-dependent K+ conductance, greatly attenuated the PbCl2-induced hyperpolarization. PbCl2 increased the intensity of fluo-3 fluorescence under both normal Ca2+ and nominally Ca(2+)-free conditions. These results suggest that Pb2+ enters thymocytes, causing an increase in fluo-3 fluorescence, and activates Ca(2+)-dependent K+ channels, resulting in hyperpolarization. The persistent activation of K+ channels by Pb2+, leading to persistent hyperpolarization, may be one mechanism whereby Pb2+ alters immune function, as membrane potential changes influence physiological functions of lymphocytes.     

Sodium-calcium exchanger contributes to membrane hyperpolarization of intact endothelial cells from rat aorta during acetylcholine stimulation

1. The role of sodium-calcium exchanger in acetylcholine (Ach)-induced hyperpolarization of intact endothelial cells was studied in excised rat aorta. The membrane potential was recorded using perforated patch-clamp technique. 2. The mean resting potential of endothelial cells was -44.1+/-1.4 mV. A selective inhibitor of sodium-calcium exchanger benzamil (100 microm) had no significant effect on resting membrane potential, but reversibly decreased the amplitude of sustained Ach-induced endothelial hyperpolarization from 20.9+/-1.4 to 5.7+/-1.1 mV when applied during the plateau phase. 3. The blocker of reversed mode of the exchanger KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate, 20 microm) reversibly decreased the amplitude of sustained Ach-induced hyperpolarization from 20.5+/-2.9 to 7.5+/-1.8 mV. 4. Introduction of tetraethylammonium (10 mm) in the continuous presence of Ach decreased the sustained phase of hyperpolarization from 17.9+/-1.5 by 12.9+/-0.9 mV. Subsequent addition of 20 microm KB-R7943 further depolarized endothelial cells by 4.8+/-1.1 mV. 5. Substituting external sodium with N-methyl d-glucamine during the plateau phase of Ach-evoked hyperpolarization reversibly decreased the hyperpolarization from -61.8+/-2.7 to -54.2+/-1.9 mV. In the majority of preparations, the initial response to removal of external sodium was a transient further rise in the membrane potential of several mV. Sodium ionophore monensin hyperpolarized endothelium by 10.3+/-0.7 mV. 6. The inhibitory effect of benzamil on Ach-induced endothelial sustained hyperpolarization was observed in endothelium mechanically isolated from smooth muscle. 7. These results suggest that the sodium-calcium exchanger of intact endothelial cells is able to operate in reverse following stimulation by Ach, contributing to sustained hyperpolarization. Myoendothelial electrical communications do not mediate the effect of blockers of sodium-calcium exchanger.     

Mode of inhibitory action of melittin on Na+-K+-ATPase activity of the rat synaptic membrane

The effects of melittin from bee venom, cardiotoxin from Formosan cobra venom, and ouabain on Na+-K+-ATPase activity of the synaptic membrane isolated from rat cerebral cortex were studied. Melittin was the most potent in inhibiting Na+-K+-ATPase activity. Mg2+-ATPase was less susceptible than Na+-K+-ATPase to the inhibitory action of toxins. High K+ (30 mM) reversed the inhibitory action of melittin on Na+-K+-ATPase but did not affect that of cardiotoxin. A comparison between the effects of ouabain and melittin was studied, using double-reciprocal plots of Na+-K+-ATPase activity against K+. It was shown that both were competitive with K+ for binding to the K+ site. Moreover, a median-effect plot revealed that ouabain and melittin antagonized each other when inhibiting Na+-K+-ATPase. Phosphatidylcholine (PC) was the only one of the phospholipids tested capable of protecting Na+-K+-ATPase from the inhibitory action of melittin but not that of ouabain. However, the inhibitory action of cardiotoxin on this enzyme was decreased by phosphatidylserine and sphingomyelin, in addition to PC. All of these findings suggest that the melittin polypeptide potently inhibits Na+-K+-ATPase, possibly by binding to the K+ site.     

Nitric oxide production and endothelium-dependent vasorelaxation induced by wine polyphenols in rat aorta

1. The aim of this work was to investigate the mechanism of vasorelaxation induced by red wine polyphenolic compounds (RWPC) and two defined polyphenols contained in wine, leucocyanidol and catechin. The role of the endothelium, especially endothelium-derived nitric oxide (NO), was also investigated.
2. Relaxation produced by polyphenols was studied in rat aortic rings with and without functional endothelium, pre-contracted to the same extent with noradrenaline (0.3 and 0.1 μM, respectively). RWPC and leucocyanidol, but not catechin, produced complete relaxation of vessels with and without endothelium. However, 1000 fold higher concentrations were needed to relax endothelium-denuded rings compared to those with functional endothelium.
3. High concentrations of catechin (in the range of 10⁻¹ g l⁻¹) only produced partial relaxation (maximum 30%) and had the same potency in rings with and without endothelium.
4. The NO synthase inhibitor, N^ω-nitro-L-arginine-methyl-ester (L-NAME, 300 μM) completely abolished the endothelium-dependent but not the endothelium-independent relaxations produced by all of the polyphenolic compounds.
5. In contrast to superoxide dismutase (SOD, 100 u ml⁻¹), neither RWPC nor leucocyanidol affected the concentration-response curve for the NO donor, SIN-1 (3-morpholino-sydnonimine) which also produces superoxide anion (O₂⁻).
6. In aortic rings with endothelium, RWPC (10⁻² g l⁻¹) produced a 7 fold increase in the basal production of guanosine 3′ : 5′-cyclic monophosphate (cyclic GMP) which was prevented by L-NAME (300 μM).
7. Electron paramagnetic resonance (e.p.r.) spectroscopy studies with Fe²⁺-diethyldithiocarbamate as an NO spin trap demonstrated that RWPC and leucocyanidol increased NO levels in rat thoracic aorta about 2 fold. This NO production was entirely dependent on the presence of the endothelium and was abolished by L-NAME (300 μM).
8. These results show that RWPC and leucocyanidol, but not the structurally closely related polyphenol catechin, induced endothelium-dependent relaxation in the rat aorta. They indicate that this effect results from enhanced synthesis of NO rather than enhanced biological activity of NO or protection against breakdown by O₂⁻. It is concluded that some polyphenols, with specific structure, contained in wine possess potent endothelium-dependent vasorelaxing activity.

     

EDRF对NE引起的大鼠主动脉缩血管效应的作用

目的：研究ＥＤＲＦ（ｅｎｄｏｔｈｅｌｉｕｍ－ｄｅｒｉｖｅｄｒｅｌａｘｉｎｇｆａｃｔｏｒ，ＥＤＲＦ）对ＮＥ（ｎｏｒｅｐｉｎｅｐｈｒｉｎｅ，ＮＥ）引起的大鼠主动脉收缩反应的影响。方法：内皮完整和去内皮的大鼠主动脉环悬挂在器官浴槽中，测定血管的张力和收缩速度的变化。所有的实验在吲哚美辛（ｉｎｄｏｍｅｔｈａｃｉｎ，１０μｍｏｌ·Ｌ－１）和普萘洛尔（ｐｒｏｐｒａｎｏｌｏｌ，３μｍｏｌ·Ｌ－１）存在下进行。结果：用甲烯蓝（ｍｅｔｈｙｌｅｎｅｂｌｕｅ，ＭＢ，１０μｍｏｌ·Ｌ－１）和左旋硝基精氨酸（ＮＧ－ｎｉｔｒｏ－Ｌ－ａｒｇｉｎｉｎｅ，Ｌ－ＮＮＡ，３０μｍｏｌ·Ｌ－１）处理内皮完整的大鼠主动脉环，ＮＥ的剂量－收缩曲线明显左移。ＥＣ３０值均降低７倍，最大反应比值分别为１．６±０．３和１．７±０．４。在去内皮的大鼠主动脉环中，经ＭＢ与Ｌ－ＮＮＡ处理后，仍可见ＥＣ３０下降３倍，最大反应比值分别为１．１±０．６和１．１±０．４。后者可能与血管平滑肌产生少量ＥＤＲＦ有关。结论：结果提示，ＮＥ对血管的收缩反应也受血管内皮和平滑肌产生的ＥＤＲＦ的调控。