Mechanisms of pinacidil-induced vasodilatation

The mechanism of the vasodilator effect of pinacidil was examined. Pinacidil (0.1–100 μM) inhibited the increases in cytosolic Ca²⁺ ([Ca²⁺]_i) and muscle tension due to norepinephrine in rat aorta. In contrast, a Ca²⁺ channel blocker, verapamil, inhibited the norepinephrine-stimulated [Ca²⁺]_i more strongly than the contraction. Higher concentrations of pinacidil (3–100 μM) inhibited the verapamil-insensitive portion of the contraction and [Ca²⁺]_i. An inhibitor of ATP-sensitive K⁺ channels, glibenclamide, antagonized the inhibitory effect of low concentrations ( 10 pM) of pinacidol. Pinacidil did not change the contraction induced by Ca²⁺ in vascular smooth muscle permeabilized with Staphylococcus aureus -toxin. Norepinephrine (in the presence of GTP), 12-deoxyphorbol 13-isobutyrate (in the absence of GTP), and treatment with GTP_γS potentiated the contraction of permeabilized smooth muscle induced by the addition of Ca²⁺. Pinacidil (100 μM) inhibited the potentiation due to GTP_γS or noepinephrine but not to phorbol ester. These results suggest that pinacidil has dual effects on vascular smooth muscle contraction. At lower concentrations (>0.1 μM), it decreases [Ca²⁺]_i, possibly by activating ATP-sensitive K+ channels. At higher concentrations (> 3 μM), it may additionally inhibit the receptor-mediated, GTP-binding protein-coupled phosphatidyl inositol turnover.     

Effect of a New Vasodilator,Pinacidil (P 1134), on Potassium,Noradrenaline and Serotonin Induced Contractions in Rabbit Vascular Tissues

Abstract: Ring preparations of rabbit aorta were contracted by potassium (127 mM). Pinacidil (P 1134), a new vasodilator (2.3×10⁻⁵ M), the calcium antagonists verapamil (3.4×10⁻⁷ M), nifedipine (3.4×10⁻⁹ M) and hydralazine (1.9×10⁴ M) relaxed the preparation by 50%. 50% relaxation of noradrenaline-contracted tissues was obtained with pinacidil, 6.8×10⁻⁵ M, verapamil, 2.4×10⁻⁴ M and hydralazine, 1.9×10⁻³ M. At 2×10⁻⁷ M concentration nifedipine was almost inactive. In ring preparations of rabbit aorta exposed to calcium-free medium and then depolarized with potassium (127 mM), pinacidil, 5×10⁻⁵ M and nifedipine, 10⁻⁸ M significantly inhibited the contractions by cumulative addition of calcium. Hydralazine, 10⁻³ M had no effect. Noradrenaline-induced contractions in calcium-free medium or in presence of increasing amounts of calcium were significantly inhibited by nifedipine, 10⁻⁸ M and hydralazine, 10⁻³ M. Pinacidil, 10⁻⁴ M had no effect. Pinacidil, 1.3×10⁻⁵ M and verapamil, 2.0×10⁻⁵ M inhibited by 50% the serotonin-induced increase of perfusion pressure of isolated rabbit ear artery. The noradrenaline effect in this preparation were 50% inhibited by pinacidil, 2.4×10⁻⁴ M and by verapamil, 8.8×10⁻⁵ M. Hydralazine, 10⁻³ M exerted minor inhibitory effect. It is suggested that interference with calcium influx contributes to the vasodilator activity of pinacidil.     

吡那地尔后处理大鼠缺血再灌注损伤心肌线粒体的蛋白质组学研究

 目的: 运用蛋白质组学研究方法探讨吡那地尔后处理对缺血再灌注损伤大鼠心肌的保护作用。方法: 建立Langendorff大鼠离体心脏缺血再灌注损伤模型,随机分为吡那地尔后处理组(Pina组)和缺血再灌注损伤组(I/R组),每组9只。提取心肌线粒体蛋白质行双向凝胶电泳,应用质谱鉴定差异大于2倍的蛋白质点。结果: Pina组与I/R组比较,共发现7个差异蛋白质:Pina组NADH脱氢酶1α亚复合体10亚基(NDUFA10)﹑NADH脱氢酶铁硫蛋白2(NDUFS2)和NADH脱氢酶黄素蛋白2(NDUFV2)表达低于I/R组;Pina组异柠檬酸脱氢酶α亚基(IDHA)和Δ^3,5-Δ^2,4-二烯酰辅酶A异构酶(ECH1)表达高于I/R组;另有2个蛋白质点均被鉴定为ATP合酶δ亚基,一个蛋白质点表达升高,而另一个表达降低。结论:吡那地尔后处理可能抑制了复合体Ⅰ的亚基(NDUFA10﹑NDUFS2和NDUFV2)代偿性增加,但促进了IDHA和ECH1表达并引发了ATP合酶δ亚基发生磷酸化,这些改变可能均与吡那地尔后处理保护心肌的作用有关。     

吡那地尔对缺氧缺糖损伤神经细胞的保护作用

目的　探讨ATP敏感性钾通道(KATP)开放剂吡那地尔(Pinacidil,Pin)对体外培养大鼠大脑皮层神经细胞缺氧缺糖损伤的保护作用。　方法　取培养10 d神经细胞,建立神经细胞缺氧缺糖损伤模型。实验分正常对照组、模型对照组、给药组(Pin和 Pin+Gli处理组),观察缺氧缺糖 4、8、16 h,再复氧24 h后神经细胞死亡率、乳酸脱氢酶(LDH)漏出量和细胞凋亡率的变化,并观察 Pin及KATP通道阻断剂格列苯脲(Gli)对其影响。　结果　经缺氧缺糖损伤后神经细胞死亡率、LDH%和细胞凋亡率均显著升高,Pin干预后,细胞死亡率(4 h: 21.42±3.68和14.83±2.94; 8 h: 36.58±6.14和19.25±3.33; 16 h: 49.17±8.3和28.64±6.4, P值均<0.01)、LDH%(4 h: 26.9±6.1和13.2±4.1; 8 h: 31.4±4.9和18.7±5.3; 16 h: 47.7±6.5和28.1±6.8, P值均<0.01)和细胞凋亡率(16 h: 42±7.8和20.4±5.5, P<0.01)均显著下降,Gli能对抗 Pin这种保护作用。　结论　KATP开放剂Pin具有直接的神经保护作用,其发挥保护作用的机制与其抑制神经细胞凋亡有关。     

吡那地尔及二氮嗪对长期低氧大鼠肺动脉平滑肌ＫＡＴＰ通道蛋白表达的影响

目的:研究慢性低氧对大鼠肺动脉平滑肌ATP敏感钾通道(KATP)蛋白表达的影响及KATP开放剂吡那地尔及二氮嗪的作用.方法:SD雄性大鼠35只随机分成对照组、低氧组、吡那地尔干预组[吡那地尔2.0 mg/(kg·d),ig]、二氮嗪干预组[二氮嗪1.5 ms/(ks·d),ig]、5-羟癸酸(5-HD) 二氮嗪干预组[5-HD 3.0 ms/(kg·d),ig;二氮嗪1.5 ms/(ks·d),ig],每组7只.将低氧组和各干预组大鼠放入常压低氧舱内[O2(10.0%±0.5%)],每周6天,每天6 h 4周后测定平均肺动脉压(mPAP)并采用Western-blot技术,分析各组肺动脉主干平滑肌KATP蛋白表达.结果:①慢性低氧组大鼠的mPAP显著高于正常对照组,吡那地尔干预组肺动脉压较低氧组显著下降.二氮嗪干预组加重慢性低氧所致的肺动脉压力升高,5.HD Z.氮嗪干预组的mPAP显著低于二氮嗪干预组,P均<0.05.②低氧组调节亚基磺酰脲受体2B(SUR2B)蛋白水平显著低于正常组,吡那地尔干预组SUR2B显著高于低氧组,二氮嗪干预组SUR2B蛋白水平显著低于低氧组,5-HD 二氮嗪干预组SUR2B显著高于二氮嗪于预组,与低氧组亦有显著统计学差异,P均<0.05.各组内向整流性孔区6.1(Kir6.1)蛋白没有显著差异(P<0.05).结论:慢性低氧抑制KATP通道蛋白的表达,而吡那地尔能提高表达,对慢性低氧所致的肺动脉高压和肺血管壁重构具有较好的预防和逆转作用;二氮嗪能加重低氧性肺动脉压升高,并抑制KATP通道蛋白的表达.     

吡那地尔预处理对兔心脏缺血再灌注时心肌炎性反应的影响

目的 评价吡那地尔预处理对兔心脏缺血再灌注时心肌炎性反应的影响.方法 日本大耳白兔56只,随机分为4组:正常对照组(C组,n=8)、缺血再灌注组(I/R组,n=16)、吡那地尔预处理组(P组,n=16)和格列本脲组(G组,n=16).建立离体心脏Langendorff再灌注模型,灌注充氧K-H液,待心率平稳10 min时,C组取心肌组织,测定丙二醛(MDA)、补体C3a、细胞间粘附分子-1(ICAM-1)和细胞核NF-κBp65表达;I/R组继续灌注充氧K-H液40 min;P组灌注充氧K-H液10 min后,灌注10 μmol/L充氧吡那地尔30 min;G组灌注10 μmol/L充氧格列本脲10 min后,再灌注10 μmol/L充氧吡那地尔30min.随后I/R组、P组和G组行全心缺血40 min,再灌注充氧K-H液.I/R组、P组和G组分别于心率平稳10 min、再灌注30、60 min时取8个心脏,测定冠状静脉流出液中肌酸激酶(CK)活性和肿瘤坏死因子-α(TNF-α)浓度;再灌注60或120 min时测定心肌组织MDA、补体C3a、ICAM-1及细胞核NF-κBp65表达.结果 P组再灌注期间CK、TNF-α、MDA、补体C3a、ICAM-1和NF-κBp65水平均明显低于其他各组(P＜0.05).结论 吡那地尔预处理可减轻兔心脏缺血再灌注时心肌炎性反应,可能与ATP敏感性钾通道开放有关,从而对心肌产生保护作用.     

含钾通道开放剂的HTK液对大鼠心功能以及线粒体结构和功能的影响

目的 观察含钾通道开放剂的供心保存液对心功能以及能量代谢、线粒体呼吸酶活性及超微结构的影响.方法 将SD大鼠分为HTK组、Pi组、5HD组、1098组和5HD+1098组.切取SD大鼠心脏,建立Langendorff灌注模型,平衡10 min,然后按分组进行如下处理:HTK组心脏以Histidine-Tryptophan-Ketoglutarate液(HTK液)停搏;Pi组心脏以含0.5 mmol/L吡那地尔(Pi)的HTK液停搏;1098组心脏以含0.5 mmol/L Pi和100 μmol/L HMR1098的HTK液停搏;5HD组心脏以含0.5 mmol/L Pi和100 μmol/L五羟葵酸(5HD)的HTK液停搏;5HD+1098组心脏以含0.5 μmol/L Pi、100 μmol/L 5HD和100μmol/L HMR1098的HTK液停搏.停搏后,将心脏置于各组相应的液体(4℃)中保存8 h,然后用含氧的37℃克-亨液(K-H液)再灌注60 min.观察各组平衡末、保存末、再灌注末时的心功能、线粒体呼吸酶活性、心肌ATP含量及心肌细胞线粒体超微结构的改变.结果 Pi组保存末、再灌注末的心功能(心率、左心室舒张末压、左心室发展压和冠状动脉流量)、心肌线粒体呼吸酶(NADH氧化酶、琥珀酸氧化酶、细胞色素C氧化酶)活性及ATP含量均优于其他各组(P<0.01或P<0.05),同时线粒体的结构改变也最轻.结论 含Pi的HTK液能改善大鼠心脏保存效果;Pi对能量状态的维持以及对线粒体结构与功能的保护可能是其心肌保护的重要机制.     

盐酸埃他卡林对正常大鼠肺内动脉平滑肌细胞钾电流的影响

目的　观察盐酸埃他卡林 (Iptakalimhydrochloride ,Ipt)对大鼠动脉平滑肌细胞钾电流的作用。方法　用胶原酶I消化、分离大鼠肺内动脉平滑肌细胞 ,用全细胞记录 (wholecellrecording)技术记录细胞钾电流 ,通过浴槽内给药 ,观察药物对钾电流的影响。结果　以给药前记录钾电流为 10 0 % ,在给予盐酸埃他卡林 1.0、10 0 .0 μmol·L-1后 ,1min记录的钾电流幅度分别为(114 .9± 3.8) % (n =8)和 (114 .0± 3.5 ) % (n =5 ) ,与溶媒对照组 (87.0± 3.5 ) % (n =8)相比 ,有显著性差异 (P <0 .0 1)。在相同条件下给予吡那地尔 (Pinacidil) 1.0 μmol·L-1后 ,钾电流幅度为 (93.6± 4 .1) % (n =8) ,与溶媒对照组相比无显著性差异(P >0 .0 5 ) ;但当吡那地尔浓度增加到 10 0 .0 μmol·L-1时 ,钾电流幅度为 (12 8.1± 13.3) % (n =4 ) ,与溶媒对照组相比有显著性差异 (P <0 .0 1)。结论　Ipt对动脉平滑肌细胞钾电流有增强作用。     

匹那地尔对大鼠缺血心肌钙调控的作用

目的 :探讨大鼠缺血心肌再灌注 (I- R)损伤的钙调控机制及匹那地尔对心肌 I- R损伤的保护作用机理。方法 :取 SD大鼠 ,心室肌细胞酶解分离 ,心肌细胞静息 1～ 2 h后随机分为 4组 :对照组、高钾停搏液组、匹那地尔强化组、格列苯脲拮抗组。 4组细胞在 2 4℃下保存 2 h后 ,复氧、复灌 2 0 min同时测定 [Ca2 + ]i 瞬态变化、肌浆网内贮钙释放功能。结果 :经匹那地尔强化处理的心肌细胞在 I- R过程中 [Ca2 + ]i 瞬态变化恢复率明显高于高钾停搏液组 (90 .2 7%～ 95 .5 7% vs6 7.0 5 %～ 80 .11% ,P<0 .0 1)。肌浆网内贮钙释放能力 (173.15 %± 2 6 .0 1% )明显高于高钾停搏液组 (112 .0 0 %± 16 .93% ) (P<0 .0 1)。经匹那地尔强化处理的心肌细胞在咖啡因诱导的钙释放后 ,胞内钙离子浓度从高水平回复到舒张末静息水平的时间为 (3.2 0± 0 .71) ms,显著短于高钾停搏液组 (3.93± 0 .4 6 ) ms(P<0 .0 5 )和对照组 (4 .6 8± 0 .77) ms(P<0 .0 1)。结论 :匹那地尔通过肌浆网和细胞膜 Na+ /Ca2 +交换体功能来调节钙瞬态变化 ,减少细胞内钙超载使心肌细胞在 I- R过程中保持较好的钙调控功能。     

The potassium channel opening action of pinacidil; studies using biochemical,ion flux and microelectrode techniques

Summary In rat aorta and rat portal vein, (–)- and (+)-pinacidil each produced a concentration-dependent inhibition of tension development. Although the (–) isomer was the more potent, concentration effect curves for each isomer were steep with similar slopes. In rat portal vein, tetraethylammonium and procaine antagonised the relaxant effect of (±)-pinacidil, whereas 3,4-diamino-pyridine was without effect. Intracellular microelectrode recording in rat portal vein showed that low concentrations of (±)-pinacidil reduced the duration of multispike electrical complexes. In both rat aorta and rat portal vein, higher concentrations of (±)-pinacidil hyperpolarised the membrane towards the potassium equilibrium potential. (±)-Pinacidil increased ⁸⁶Rb efflux from rat aorta and rat portal vein in a concentration dependent manner. In a separate study, (±)-pinacidil increased ⁴²K efflux from rat portal vein. (±)-Pinacidil had no effect on cyclic GMP or cyclic AMP levels in rat aorta. It is concluded that pinacidil opens ⁸⁶Rb-permeable potassium channels in rat aorta and rat portal vein. This mechanism is independent of cyclic nucleotide changes and may be responsible for the antihypertensive effect of pinacidil. Send offprint requests to: A. H. Weston at the above address