Regulation of NO-dependent acetylcholine relaxation by K channels and the Na-K ATPase pump in porcine internal mammary artery

This study was designed to determine whether K⁺ channels play a role in nitric oxide (NO)-dependent acetylcholine relaxation in porcine internal mammary artery (IMA). IMA segments were isolated and mounted in organ baths to record isometric tension. Acetylcholine-elicited vasodilation was abolished by muscarinic receptor blockade with atropine (10^-6 M). Incubation with indomethacin (3 × 10⁻⁶ M), superoxide dismutase (150 U/ml) and bosentan (10⁻⁵ M) did not modify the acetylcholine response ruling out the participation of cyclooxygenase-derivates, reactive oxygen species or endothelin. The relaxation response to acetylcholine was strongly diminished by NO synthase- or soluble guanylyl cyclase-inhibition using l-NOArg (10⁻⁴ M) or ODQ (3 × 10⁻⁶ M), respectively. The vasodilation induced by acetylcholine and a NO donor (NaNO₂) was reduced when rings were contracted with an enriched K⁺ solution (30 mM), by voltage-dependent K⁺ (K_v) channel blockade with 4-amynopiridine (4-AP; 10⁻⁴ M), by Ca²⁺-activated K⁺ (K_Ca) channel blockade with tetraethylammonium (TEA; 10⁻³ M), and by apamin (5 × 10⁻⁷ M) plus charybdotoxin (ChTx; 10⁻⁷ M) but not when these were added alone. In contrast, large conductance K_Ca (BK_Ca)_, ATP-sensitive K⁺ (K_ATP) and inwardly rectifying K⁺ (K_ir) channel blockade with iberiotoxin (IbTx; 10⁻⁷ M), glibenclamide (10⁻⁶ M) and BaCl₂ (3 × 10⁻⁵ M), respectively, did not alter the concentration-response curves to acetylcholine and NaNO₂. Na⁺−K⁺ ATPase pump inhibition with ouabain (10⁻⁵ M) practically abolished acetylcholine and NaNO₂ relaxations. Our findings suggest that acetylcholine-induced relaxation is largely mediated through the NO-cGMP pathway, involving apamin plus ChTx-sensitive K⁺ and K_v channels, and Na⁺−K⁺-ATPase pump activation.     

Contractile responses of human deferential artery and vas deferens to vasopressin

We studied the effects of vasopressin on isolated rings of human deferential artery and vas deferens (prostatic portion) obtained from patients undergoing radical cystectomy (n = 11) or prostatectomy (n = 10). Ring segments of artery or vas deferens were studied in organ bath experiments at optimal resting tension. In artery rings, vasopressin produced concentration-dependent, endothelium-independent contractions with an EC₅₀ of 4.5 × 10⁻¹⁰ M. The presence of N^G-nitro- -arginine methyl ester hydrochloride (10⁻⁴ M), an inhibitor of nitric oxide synthase, did not change significantly (P > 0.05) the vasopressin-induced contraction. In ring preparations of the prostatic part of the vas deferens, vasopressin induced phasic contractions with an EC₅₀ of 7.0 × 10⁻⁹ M. The vasopressin V₁ receptor antagonist, d(CH₂)₅Tyr(Me)AVP (10⁻⁸ and 10⁻⁶), displaced to the right in parallel the control curve to vasopressin in artery and vas deferens rings. These results indicate that vasopressin exerts a powerful constrictor action on human deferential artery and vas deferens by direct stimulation of V₁ receptors. It is concluded that the deferential artery may dampen the passage of blood to the vas deferens in circumstances characterized by increased plasma vasopressin levels.     

The comparison of the responsiveness of human isolated internal mammary and gastroepiploic arteries to levcromakalim: an alternative approachto the management of graft spasm

Aims We studied the effectiveness of levcromakalim, a potassium channel opener (KCO), in the prevention and reversal of spasm in arterial grafts used in coronary artery bypass operations, namely, internal mammary artery (IMA) and gastroepiploic artery (GEA).
Methods Spasm was mimicked in vitro in arterial rings from 109 patients by increasing the vascular tension with noradrenaline, the thromboxane analogue U46619, endothelin-1 and K⁺ .
Results GEA displayed considerably higher contractile force to these agents than IMA. Pretreatment with levcromakalim depressed significantly the maximal contractile responses (either absolute or relative) to noradrenaline and U46619 but did not affect those of endothelin-1 and K⁺ in both of the arteries. Sensitivities (to all agents, except to endothelin-1) decreased significantly after levcromakalim. In experiments evaluating the antispasmodic activity of levcromakalim, a higher relaxant capacity was observed in GEA than IMA (for K⁺ contraction; IMA: 31.32±3.83%, n =13 vs GEA: 98.01±0.71%, n =7, P <0.05). This different activity of levcromakalim between two arterial grafts was apparent even when GEA rings were contracted to higher force (g) than that of IMA (for K⁺ contraction; GEA: 72.56±4.96%, n =7). Responses to levcromakalim were similar in IMA and GEA when endothelin-1 was used as the spasmogenic agent (IMA: 80.98±4.85%, n =10 vs GEA: 91.93±3.17%, n =7, P >0.05).
Conclusions Our results provide evidence that levcromakalim may have a therapeutic value in the treatment of spasm of coronary artery bypass grafts, especially GEA.     

非体外循环全动脉化冠状动脉旁路移植术的应用与疗效观察

目的 探讨全动脉化冠状动脉旁路移植术的手术技术。方法 36例接受全动脉化冠状动脉旁路移植术的患者,全组取左乳内动脉（IMA）36例,双侧IMA8例,左桡动脉（RA）19例,右桡动脉（RA）4例,双侧RA10例。结果 术后1例患者因多器官功能衰竭死亡（死亡率2.7%）,25例（97.3写）症状明显改善,康复出院。结论 全动脉化搭桥手术早期临床效果满意。     

经桡动脉途径行左内乳动脉造影的临床分析

目的 探讨经桡动脉途径开展左内乳动脉造影的安全性和有效性.方法 对181例（男119例,女62例）患者经桡动脉途径,采用6F JL3.5冠脉造影导管行左内乳动脉造影.结果 有170例完成左内乳动脉造影,总成功率94.0%,且左内乳动脉造影均获显影满意结果.左内乳动脉造影失败主要原因为主动脉弓迂曲（7例,男6例,女1例;占4%）;桡动脉痉挛（4例,男1例,女3例;占2%）.术后左臂部肿胀淤血4例（2.2%）;左前臂穿刺点近端至肘关节处肿胀淤血7例（3.9%）;穿刺点周围皮肤红疱疹5例（2.8%）.无右桡动脉闭塞、动静脉瘘、假性动脉瘤、穿刺口皮肤破溃感染及前臂骨筋膜室综合征发生.结论 经桡动脉途径行左内乳动脉造影是一种安全、有效、易于接受的检查手段.     

血管内支架成形术治疗颈内动脉高度狭窄的临床研究

目的 评价血管内支架成形术(CAS)治疗颈内动脉狭窄的临床应用价值。方法 选择颈内动脉狭窄≥80％的患者38例，全部均行全脑血管造影(CAG)、颈部超声和经颅多普勒(TCD)检查，并采用3种不同支架治疗；6月后复查上述检查。结果 38例操作顺利，临床并发症少，3例(7．9％)发生短暂性脑块血发作(TIA)，1例(2．6％)发生脑栓塞，3例(7．9％)发生过度灌注综合征；所有病例影像学评价成功，TCD检查血流恢复正常或明显好转；33例(86．8％)临床症状完全消失，3例(7．9％)好转；6月后CAG显示仅2例(5．3％)发生血管再狭窄。结论 CAS技术治疗颈内动脉高度狭窄是一种安全有效的新方法，值得推广应用。     

雄激素对大鼠主动脉一氧化氮合酶/一氧化氮体系的调节

目的：研究雄激素对大鼠主动脉一氧化氮合酶／一氧化氮(NOS／NO)体系的影响，以探讨雄激素对心血管系统的作用。方法：将30只雄性大鼠随机分为三个组，每组10只，去卵巢组(A组)、去卵巢 雄激素组(B组)、假手术组(C组)。正常饮食2个月后处死大鼠，测血清雄激素、主动脉匀浆一氧化氮合酶活性及一氧化氮含量。结果：同假手术组相比。去势大鼠主动脉匀浆NOS活性及NO含量显著降低，在补充适量的雄激素后．主动脉匀浆NOS活性及NO含量显著上升。结论：雄激素可以调节大鼠动脉内一氧化氮合酶／一氧化氮体系，可能是其调节血管张力的作用机制。     

Regulation of vascular tone in rabbit ophthalmic artery: Cross talk of endogenous and exogenous gas mediators

Nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H₂S) modulate vascular tone. In view of their therapeutic potential for ocular diseases, we examined the effect of exogenous CO and H₂S on tone of isolated rabbit ophthalmic artery and their interaction with endogenous and exogenous NO. Ophthalmic artery segments mounted on a wire myograph were challenged with cumulative concentrations of phenylephrine (PE) in the presence or absence of N^G-nitro-l-arginine (LNNA) to inhibit production of NO, the CO-releasing molecules CORMs or the H₂S-donor GYY4137. The maximal vasoconstriction elicited by PE reached 20–30% of that induced by KCl but was dramatically increased by incubation with LNNA. GYY4137 significantly raised PE-mediated vasoconstriction, but it did not change the response to PE in the presence of LNNA or the relaxation to sodium nitroprusside (SNP). CORMs concentration-dependently inhibited PE-induced constriction, an effect that was synergistic with endogenous NO (reduced by LNNA), but insensitive to blockade of guanylyl cyclase by 1H-[1,2,4]oxadiazolo[4,3,-α]quinoxalin-1-one (ODQ). In vascular tissues cyclic GMP (cGMP) levels seemed reduced by GYY4137 (not significantly), but were not changed by CORM. These data indicate that CO is able per se to relax isolated ophthalmic artery and to synergize with NO, while H₂S counteracts the effect of endogenous NO. CO does not stimulate cGMP production in our system, while H₂S may reduce cGMP production stimulated by endogenous NO. These findings provide new insights into the complexities of gas interactions in the control of ophthalmic vascular tone, highlighting potential pharmacological targets for ocular diseases.     

Mechanisms underlying impairment of endothelium-dependent relaxation by fetal bovine serum in organ-cultured rat mesenteric artery

Organ culture of blood vessels provides a useful technique to investigate long-term effects of drugs because tissue architecture and function are well preserved. Various growth factors are responsible for structural and functional changes during vascular diseases. We investigated long-term effects of fetal bovine serum (FBS) which contains such factors on endothelium-dependent relaxation using organ-culture method. Rat isolated mesenteric arteries with endothelium were cultured for 3 days without or with 10% FBS (FBS). Acetylcholine- and bradykinin-induced endothelium-dependent relaxations were significantly impaired in FBS, whereas sodium nitroprusside-induced relaxation of endothelium-removed artery was unchanged. Morphological examination revealed that endothelium was intact in FBS. Acetylcholine-induced nitric oxide (NO) release as detected by 4, 5-diaminofluorescein significantly decreased in FBS, whereas endothelial NO synthase expression was unchanged. A Ca²⁺ ionophore, A23187-induced relaxation was unchanged in FBS. A phospholipase C activator, m-3M3FBS-induced relaxation of FBS was unchanged in either Ca²⁺-containing or -free solution. Total expressions of transient receptor potential canonical channels (TRPCs: TRPC-1, -4, -5) were similar in FBS. These data suggest that FBS impairs endothelium-dependent relaxation by inhibiting events upstream of phospholipase C activation including phospholipase C, G-protein, and receptors in endothelium.     

慢性阻塞性肺疾病患者两种舒血管因子水平的临床研究

目的研究慢性阻塞性肺疾病(COPD)患者血清一氧化氮(NO)和肾上腺髓质素(ADM)的变化及意义。方法选择COPD急性加重期患者50例,分为Ⅰ级、Ⅱ级、Ⅲ级、Ⅳ级4组,应用硝酸还原酶法测定NO,酶联免疫吸附法测定肾上腺髓质素(ADM)水平,并记录动脉血气分析、肺功能等指标。同时与13例健康者进行对照。结果①COPD组血清NO较对照组显著降低,差异具有统计学意义(P<0.01),COPD组较对照组显著增高,差异具有统计学意义(P<0.01);②血清NO、ADM值随COPD分级增高而变化,且组间差异有统计学意义(P<0.05);③NO与FEV1、PaO2呈正相关,与PaCO2呈负相关;ADM与FEV1、PaO2呈负相关,与PaCO2呈正相关;NO与ADM呈负相关。结论 NO和ADM作为肺脏重要的舒血管因子,以不同的方式参与和影响了COPD的发生和发展。     

Effect of engineered nanoparticles on vasomotor responses in rat intrapulmonary artery

Pulmonary circulation could be one of the primary vascular targets of finest particles that can deeply penetrate into the lungs after inhalation. We investigated the effects of engineered nanoparticles on vasomotor responses of small intrapulmonary arteries using isometric tension measurements. Acute in vitro exposure to carbon nanoparticles (CNP) decreased, and in some case abolished, the vasomotor responses induced by several vasoactive agents, whereas acute exposure to titanium dioxide nanoparticles (TiO₂NP) did not. This could be attributed to a decrease in the activity of those vasoactive agents (including PGF_2α, serotonin, endothelin-1 and acetylcholine), as suggested when they were exposed to CNP before being applied to arteries. Also, CNP decreased the contraction induced by 30 mM KCl, without decreasing its activity. After endoplasmic reticulum calcium stores depletion (by caffeine and thapsigargin), CaCl₂ addition induced a contraction, dependent on Store-Operated Calcium Channels that was not modified by acute CNP exposure. Further addition of 30 mM KCl elicited a contraction, originating from activation of Voltage-Operated Calcium Channels that was diminished by CNP. Contractile responses to PGF_2α or KCl, and relaxation to acetylcholine were modified neither in pulmonary arteries exposed in vitro for prolonged time to CNP or TiO₂NP, nor in those removed from rats intratracheally instilled with CNP or TiO₂NP. In conclusion, prolonged in vitro or in vivo exposure to CNP or TiO₂NP does not affect vasomotor responses of pulmonary arteries. However, acute exposure to CNP decreases contraction mediated by activation of Voltage-Operated, but not Store-Operated, Calcium Channels. Moreover, interaction of some vasoactive agents with CNP decreases their biological activity that might lead to misinterpretation of experimental data.     

Inhibition of vasoconstriction by potassium channel opener aprikalim in human conduit arteries used as bypass grafts

Aims Potassium channel openers (KCOs) are of potential therapeutic value. Little is known about the effect of these drugs on human conduit arteries used as coronary bypass grafts. The purpose of this study was to determine the effect of the KCO aprikalim (RP52891) on human arteries used as coronary bypass grafts with emphasis on the possible difference in the inhibitory effect on depolarizing agent-mediated rather than receptor-mediated contraction. Methods Human internal mammary artery segments (IMA, n=88) taken from 28 patients were studied. Concentration-relaxation curves for aprikalim were established in IMA precontracted with three vasoconstrictors (K⁺, U46619, and phenylephrine). In IMA rings incubated with aprikalim (1 or 30 μm ) for 10 min concentration-contraction curves for the three vasoconstrictors were constructed. Results Aprikalim-induced relaxation was less in K⁺ (37.3±6.4%) than in U46619 (80.2±7.7%, P=0.002), or phenylephrine (67.5±7.0%, P=0.038) -precontracted IMA. The EC₅₀ for K⁺-(−5.40±0.12 log m ) was significantly higher than that for phenylephrine (−6.43±0.30 log m, P=0.007) but not significant compared with that for U46619 (−5.81±0.11, P >0.05). Pretreatment with aprikalim depressed the contraction by phenylephrine from 140.6±27.6% to 49.3±14.1% (P=0.002) and shifted the EC₅₀ 11.0-fold higher in rings treated with 1 μm aprikalim (P=0.007). Treatment of aprikalim did not significantly reduce the K⁺ and U46619-induced contraction (P >0.05) but shifted the concentration-contraction curves rightward (2.8-fold higher for K⁺, P<0.05 and 2.2-fold higher for U46619, P<0.05). Conclusions This study demonstrates that aprikalim has vasorelaxant effects in human conduit arteries used as coronary artery bypass grafts contracted by a variety of vasoconstrictors and this effect is vasoconstrictor-selective with greater potency for α₁-adrenoceptor agonists than for depolarizing agent K⁺. These findings provide information on the possible use of this KCO in various clinical settings.     

Mechanisms underlying diabetes enhancement of endothelin-1-induced contraction in rabbit basilar artery

The influence of alloxan-induced diabetes on the reactivity of rabbit basilar artery to endothelin-1 was examined. Endothelin-1 induced concentration-dependent contraction of basilar arteries that was higher in diabetic than in control rabbits. Endothelium removal produced a higher enhancement of the endothelin-1-induced contraction in control than in diabetic rabbits. N(G)-nitro-L-arginine (L-NOArg) enhanced the maximal contraction induced by endothelin-1 in control rabbits and potentiated this response in diabetic rabbits. Endothelin ETA receptor antagonist, cyclo(D-Asp-Pro-D-Val-Leu-D-Trp) (BQ-123), inhibited endothelin-1-induced contraction in both rabbit groups. Endothelin ETB receptor antagonist, 2,6-Dimethylpiperidinecarbonyl-gamma-Methyl-Leu-Nin-(Methoxycarbonyl)-D-Trp-D-Nle (BQ-788), enhanced endothelin-1-induced contraction in control rabbits and decreased the potency of endothelin-1 in diabetic rabbits. Sodium nitroprusside-induced relaxation of basilar arteries was lower in diabetic than in control rabbits. These results suggest that mechanisms underlying rabbit basilar artery hyperreactivity to endothelin-1 include decreased endothelial modulation of endothelin-1-induced contraction, with impaired endothelial endothelin ETB receptor activity; decreased sensitivity to nitric oxide (NO) in vascular smooth muscle; and enhanced participation of muscular endothelin ETA and ETB receptors.     

淫羊藿苷对离体大鼠胸主动脉环舒缩功能和左心室内压的影响

目的:研究淫羊藿苷体外给药对大鼠离体胸主动脉环舒缩功能和左心室内压的影响以及其可能的机制。方法:取正常大鼠胸主动脉和心脏,制成胸主动脉环和完整的离体心脏,观察不同浓度淫羊藿苷对胸主动脉环张力和左心室内压的影响。结果:淫羊藿苷能够剂量依赖性的舒张内皮完整的胸主动脉环,降低胸主动脉环的收缩张力,L-硝基精氨酸(NLA)能够减弱淫羊藿苷的舒血管作用。淫羊藿苷还能够降低离体大鼠心脏左心室收缩峰压(LVSP)、最大上升速率(+dp/dt)。结论:淫羊藿苷能舒张离体胸主动脉环,降低心脏收缩力,并且其舒血管效应与内皮和一氧化氮(NO)相关。     

不同方法固定的细胞色素C对一氧化氮的响应性能

目的　比较不同方法固定的细胞色素C(CytC)对一氧化氮(NO)的响应性能。方法　以不同的溶胶凝胶法对CytC进行固定,并通过UV法考察固定化CytC的性质及其对一氧化氮响应的性能。结果　以硅溶胶法固定的CytC膜性质较好,对NO的响应时间较快,敏感度较高,可逆速度快,重复性好,NO在1 2 3～2 85 μmol·L-1 范围内与吸光度线性关系良好(r =0 . 9995 )。结论　为进一步研制NO光学传感器奠定了基础。     

The effects of extended nitric oxide release on responses of the human non-pregnant myometrium to endothelin-1 or vasopressin

BackgroundUterotonic mediators: endothelin-1 (ET-1), arginine vasopressin (AVP), and nitric oxide (NO) play important roles in the regulation of uterine contractility. We hypothesize that NO affects both ET-1 or AVP. Therefore, this study investigated the involvement of extended exogenous NO release in the regulation of responses of the human non-pregnant myometrium to ET-1 and AVP.MethodsSpecimens were obtained from 10 premenopausal women, undergoing hysterectomy for benign gynecological disorders. Responses of the myometrial strips to ET-1 or AVP in the absence and presence of an exogenous NO donor (diethylenetriamine; DETA/NO; 10⁻⁴ mol/L) were recorded under isometric conditions. To inhibit endogenous NO, a competitive inhibitor of NO synthase, L-N^G-nitroarginine (L-NNA) was added to the organ bath.ResultsET-1 enhanced the spontaneous contractile activity of the myometrium more powerfully (p < 0.01) than AVP. Preincubation with exogenous NO weakened ET-1- or AVP-induced increases in this contractile activity (p < 0.05). However, unexpected results were obtained after preincubation with L-NNA and with DETA/NO then added. Both ET-1 and AVP induced augmented contractile effects in almost all concentrations compared with the responses to these peptides alone or after NOS synthase inhibition (both p < 0.01).ConclusionsThis study demonstrated for the first time that extended incubation with a NO donor influences the uterine muscle response evoked by ET-1 and AVP. Both endogenous and exogenous NO is involved in the control of the uterine responses to ET-1 or AVP of non-pregnant myometrium. Furthermore, both peptides stimulate increased uterine contractility when the local imbalance between the constrictive and relaxing mediators takes place.     

Influence of oxygen, temperature and carbon dioxide on nitric oxide formation from nitrite as measured in expired gas from in situ perfused rabbit lungs

In biological systems, nitric oxide (NO) may be generated non-enzymatically from nitrite (nitrite-derived NO), in addition to nitric oxide synthase-catalyzed (NOS-derived) L-arginine-dependent formation. Through recordings of expired NO, we studied the influence of temperature on NOS- and nitrite-derived NO in the perfused lung. We also studied the impact of other influencing factors (O(2), CO(2), and pH) on nitrite-derived NO in the same system. Both NO-generating systems exhibited biphasic temperature dependence with a positive correlation between temperature and NO generation that peaked between 42 and 44 degrees C. The nitrite-derived NO generation was enhanced by hypoxia alone (>20 x after 5 min) and further by concomitant increase in CO(2). The CO(2) effect could not be explained by changes in extracellular pH and was unaltered by acetazolamide. We conclude that the temperature dependence in the known enzyme-catalyzed NOS-derived NO and especially in the nitrite-derived NO strengthens the hypothesis that an enzyme could be involved in nitrite-derived NO formation. The enhancement of nitrite-derived NO by increases in CO(2) suggests that this system could be of importance to improve perfusion in ischemic tissues.     

Effect of hydroxocobalamin on vasodilatations to nitrergic transmitter, nitric oxide and endothelium-derived relaxing factor in guinea-pig basilar artery

In endothelium-denuded guinea-pig isolated basilar artery preparations, hydroxocobalamin (30, 100 and 300 μM) concentration-dependently inhibited the vasodilator responses to exogenous nitric oxide (NO), whereas the vasodilator responses to nitrergic nerve stimulation were slightly reduced by high (100 and 300 μM) but not by the low (30 μM) concentration of hydroxocobalamin. Vasodilatation in response to sodium nitroprusside (10–100 nM) was totally abolished by 300 μM hydroxocobalamin. In endothelium-intact preparations, vasodilator responses to acetylcholine (0.3–3 μM) were significantly reduced or abolished by hydroxocobalamin (30–300 μM). The mean reduction by hydroxocobalamin of relaxations to acetylcholine was significantly greater than that of the equivalent response evoked by nitrergic nerve stimulation. The findings suggest that the nitrergic transmitter in the guinea-pig basilar artery may be quantitatively less susceptible than the endothelium-derived relaxing factor to the NO scavenger hydroxocobalamin.     

髂内动脉结扎加尿流改道术治疗顽固性出血性放射性膀胱炎

目的 评价双侧髂内动脉结扎加尿流改道术治疗顽固性出血性放射性膀胱炎的临床效果.方法 8例患者均因盆腔肿瘤放疗后出现反复出血的放射性膀胱炎,进行双侧髂内动脉结扎加尿流改道术.结果 术后3 h,8例患者血尿明显缓解,3 d内血尿基本消失,尿频、尿急渐消失.随访6～24个月,均无严重的血尿复发.结论 双侧髂内动脉结扎加尿流改道术是一种治疗顽固性出血性放射性膀胱炎的有效方法.