Effects of l-tetrahydropalmatine on isolated rabbit arterial strips

The effects of l-tetrahydropalmatine (THP) on isolated rabbit aortic, renal and superior mesenteric arterial strips were studied in comparison with verapamil (Ver). THP and Ver shifted the KCl, CaCl2, norepinephrine (NE) and 15-methyl prostaglandin F2 alpha dose-response curves to the right in a non-parallel fashion, and decreased the maximal response, showing noncompetitive antagonism. THP was less potent in dilating arterial strips than Ver. THP and Ver obviously inhibited the intracellular Ca2+-dependent component of NE-induced contraction of the aorta, but only slightly decreased the extracellular Ca2+-dependent component when the concentration of THP or Ver was very high (THP 0.1 mmol/L, Ver 10 mumol/L). The results suggest that THP, similar to Ver, mainly inhibits potential-operated calcium channels. THP and Ver were more potent in dilating renal and superior mesenteric arterial strips than aortic strips. The results indicate that the vasodilation effect of THP is similar to that of Ver and that THP probably has a calcium antagonistic effect.     

蛇床子素对家兔主动脉条的钙拮抗作用

蛇床子素30μmol·L~(-1)及100μmol·L~(-1)使NE、CaCl_2和高K~+除极化所致的家兔主动脉条收缩量—效曲线右移,最大反应降低.表明蛇床子素有松弛血管平滑肌作用,并与Ca~(2+)呈非竞争性拮抗作用.和阻滞α受体或激动β受体无关;选择性作用于电位依赖性Ca~(2+)通道,抑制细胞外Ca~(2+)内流;在100μmol·L~(-1)时,明显减弱NE诱导的依赖细胞内Ca~(2+)收缩。证明蛇床子素松弛血管平滑肌作用可能与其Ca~(2+)拮抗作用有关。     

灯盏花素抑制去甲肾上腺素而增强高钾缩血管反应

目的　观察灯盏花素 (Bre)对去甲肾上腺素 (NA)和高钾所致缩血管反应的影响 ,研究其效应与细胞内游离钙浓度([Ca2 + ]i)变化的关系。方法　采用兔胸主动脉条 ,观察Bre对NA及高钾缩血管量效曲线、对NA和咖啡因在无钙液中所致短暂收缩及复钙后NA缩血管反应的影响 ;利用Fura 2 /AM负载的兔血管平滑肌细胞 ,观察在Bre存在下 ,由NA及高钾所增加的 [Ca2 + ]i的变化。结果　Bre呈剂量依赖性地使NA缩血管量效曲线非平行右移 ,最大反应压低 ,对高钾的量效曲线却呈增强作用 ;该药抑制NA及咖啡因在无Ca2 + 液中所诱发的短暂收缩及复Ca2 + 后NA所致缩血管反应 ;Bre抑制NA所致平滑肌 [Ca2 + ]i 的升高 ,而增强高钾升高 [Ca2 + ]i 的作用。结论　Bre通过抑制Ca2 + 内流和Ca2 +释放而抑制NA所致血管平滑肌的收缩 ,通过增强高钾所致Ca2 + 内流而增强其缩血管效应 ,但Bre增强高钾升高[Ca2 + ]i 的作用原理尚有待探讨     

Vasorelaxing effect in rat thoracic aorta caused by denudatin B, isolated from the Chinese herb, magnolia fargesii

Denudatin B is an antiplatelet agent isolated from the flower buds of Magnolia fargesii. We studied the effects of denudatin B on the vasoconstriction of rat thoracic aorta induced by high potassium (K+) solution, norepinephrine (NE) and caffeine, and to elucidate its mode of action. The contraction of rat aorta caused by high K+ (60 mM) and cumulative concentrations of CaCl2 (0.03-3 mM) was inhibited concentration dependently by denudatin B with an IC50 of 21.2 micrograms/ml. NE (3 microM)-induced phasic and tonic contractions of rat aorta were inhibited by pretreatment with denudatin B (10-100 micrograms/ml). The relaxing action of denudatin B persisted in denuded aorta, in Ca2(+)-free and EGTA (2 mM)-containing medium. The vasorelaxing effects were not affected by indomethacin (20 microM), hemoglobin (10 microM) or methylene blue (50 microM) and were not accompanied by PGI2 formation. In quin-2/AM-loaded cultured rat vascular smooth muscle cells, denudatin B (100 micrograms/ml) inhibited the increase of intracellular calcium caused by NE (3 microM) in the presence or absence of extracellular calcium. Denudatin B did not affect the caffeine (10 mM)-induced contraction and the increase in intracellular calcium. Denudatin B (100 micrograms/ml) increased the cGMP, but not the cAMP level in intact and denuded aorta. The 45Ca2+ influx induced in rat aorta by high K+ (60 mM) or NE (3 microM) was markedly inhibited by denudatin B in a concentration-dependent manner. These results indicate that denudatin B relaxed vascular smooth muscle by inhibiting the Ca2+ influx through voltage-gated and receptor-operated Ca2+ channels; its effect to increase cGMP may enhance the vasorelaxation.     

大黄素和番泻甙A对兔主动脉收缩作用的影响

观察大黄素（Ｅｍｄ）和番泻甙Ａ（ＳｅｎＡ）对ＮＥ和高Ｋ＋诱导的兔主动脉条（ＲＡ）收缩作用的影响。结果表明，小剂量大黄素（１８．５μｍｏｌ·Ｌ－１）和番泻甙Ａ均可使ＮＥ和高Ｋ＋诱导的ＲＡ收缩的量效曲线左移，其作用原理可能与钙激动作用有关。大剂量大黄素（９２．５μｍｏｌ·Ｌ－１）抑制ＲＡ收缩作用，量效曲线右移，其作用可能与大黄素络合游离Ｃａ２＋作用有关。     

瓜蒌提取物对离体家兔胸主动脉条收缩的影响

以兔离体主动脉条为实验材料,观察ＥＦＴ对去甲肾上腺素（ＮＥ）、氯化钾（ＫＣｌ）和氯化钙（ＣａＣｌ２）的剂量－效应曲线的影响及主动脉条的α受体及β受体的作用．观察了ＥＦＴ对ＮＥ引起的兔主动脉条２种收缩成分的影响．结果ＥＦＴ能舒张已被氯化钙、高钾和去甲肾上腺素收缩的兔主动脉条,使ＮＥ、ＫＣｌ、ＣａＣｌ２的剂量－效应曲线非平行右移,最大效应降低．ＥＦＴ松驰血管平滑肌的作用不依赖于阻断α受体或β受体．而与戊脉安（Ｖｅｒ）相似,是通过阻断钙通道实现的．但它们阻断钙通道的方式不同．ＥＦＴ可能无选择性阻断电位依赖性钙通道和受体操纵性钙通道,而Ｖｅｒ则只选择性阻断．因此,ＥＦＴ的扩血管机制与其对钙通道阻断作用有关     

阿司匹林铜对离体兔主动脉血管条收缩的影响(英文)

目的:观察阿司匹林铜对离体免胸主动脉血管平滑肌的作用。方法:取免胸主动脉条,观察阿司匹林铜对去甲肾上腺素(NE)、KCl、CaCl_2诱导收缩作用的影响。结果:证实阿司匹林铜和对照物硫酸铜拮抗NE诱导的兔胸主动脉条收缩,IC_(50)分别为31nmol/L和0.29μmol/L,而阿司匹林本身没有拮抗作用。阿司匹林铜对KCl、CaCl_2诱导的收缩没有影响。在去内皮细胞兔胸主动脉条上,观察到相同的作用。结论:阿司匹林铜具有较强的拮抗NE诱导离体兔胸主动脉条收缩的作用,但不能拮抗KCl、CaCl_2诱导的收缩,提示阿司匹林铜通过阻断受体调控钙通道,舒张血管平滑肌。     

淫羊藿甙扩血管作用机制的研究

本实验以离体兔胸主动脉条为标本，对淫羊藿甙（ＥＩ）扩血管作用的机制进行了探讨。ＥＩ２０，４０ｍｇ·Ｌ－１对ＮＥ、ＫＣｌ及ＣａＣｌ２收缩兔主动脉条的量效曲线呈非竞争性拮抗作用；ＥＩ３０ｇ·Ｌ－１能明显抑制ＮＥ诱导的兔主动脉条依赖于细胞外钙的收缩反应，对依赖于细胞内钙的收缩反应没有影响；ＥＩ３０ｇ·Ｌ－１松驰主动脉条的作用与阻断α受体或激动β受体无关。提示ＥＩ的扩血管作用机制可能与其对钙通道的阻滞作用有关。     

Vasorelaxation of rat thoracic aorta caused by norathyriol isolated from Gentianaceae.

The pharmacological effects of norathyriol on isolated rat thoracic aorta were examined. In the high-K+ (60 mM) medium, Ca2+ (0.03 to 3 mM)-induced vasocontraction was inhibited concentration dependently by norathyriol. Given as pretreatment norathyriol (20 to 200 microM) also inhibited the norepinephrine (NE, 3 microM)-induced tonic contraction. However, the phasic contraction was inhibited only by high concentrations of norathyriol (200 and 400 microM). The tonic contraction elicited by NE was also relaxed by the addition of norathyriol. This relaxing effect of norathyriol was not antagonized by methylene blue (50 microM) or indomethacin (20 microM) and was still seen in denuded rat aorta. Although the cAMP level was not changed by norathyriol, the cGMP level was increased by a high concentration of norathyriol (400 microM). [3H]Inositol monophosphate formation caused by NE was not affected by norathyriol at concentration of either 100 or 400 microM. The 45Ca2+ influx caused by either NE or high K+ was inhibited by norathyriol in a concentration-dependent manner. It is concluded that norathyriol relaxed the rat thoracic aorta mainly by suppressing the Ca2+ influx through both voltage-dependent and receptor-operated calcium channels.     

Ca(2+)-channel blockade in rat thoracic aorta by protopine isolated from Corydalis tubers.

The pharmacological properties and mechanism of the action of protopine on isolated rat thoracic aorta were examined. It inhibited norepinephrine (NE, 3 microM)-induced tonic contraction in rat thoracic aorta in a concentration-dependent manner (25-100 micrograms/ml). The phasic contraction caused by NE was inhibited only by a high concentration of protopine (100 micrograms/ml). At the plateau of NE-induced tonic contraction, the addition of protopine also caused relaxation. This relaxing effect of protopine was not antagonized by indomethacin (20 microM) or methylene blue (50 microM), and it still existed in denuded rat aorta or in the presence of nifedipine (2-100 microM). Protopine also inhibited high potassium (60 mM)-induced, calcium-dependent (0.03-3 mM) contraction of rat aorta in a concentration-dependent manner. Neither cAMP nor cGMP level was changed by protopine. Both the formation of inositol monophosphate caused by NE and the phasic contraction induced by caffeine were also not affected by protopine. 45Ca2+ influx caused by either NE or K+ was inhibited by protopine concentration-dependently. It is concluded that protopine relaxed the rat thoracic aorta mainly by suppressing the Ca2+ influx through both voltage- and receptor-operated calcium channels.     

薤白提取物对兔离体主动脉条的作用

本实验以离体兔主动脉条为标本 ,对薤白 (EA)的扩血管机制进行了探讨 .观察了薤白对去甲肾上腺素 (NE)、氯化钾 (KCl)和氯化钙 (CaCl2 )的剂量 效应曲线的影响及主动脉条的α受体及 β受体的作用 .观察了EA对NE引起的兔主动脉条两种收缩成分的影响 .结果表明EA能舒张已为氯化钙、高钾和去甲肾上腺素收缩的兔主动脉条 ,使NE、KCl、CaCl2 的剂量 效应曲线非平行右移 ,最大效应降低 .EA松弛血管平滑肌的作用不依赖于阻断α受体或 β受体 ,而与戊脉安 (Ver)相似 ,是通过阻断钙通道实现的 .但它们阻断钙通道的方式不同 .EA可能无选择性阻断电位依赖性钙通道和受体操纵性钙通道 .因此EA的扩血管机制与其对钙通道阻断作用有关 .     

Inhibitory effect of disodium quercetin-7,4'-disulfate on aggregation of pig platelets induced by thrombin and its mechanism

AIM: To study the inhibitory effect of semi-synthesized quercetin derivatives--disodium quercetin-7,4'-disulfate (DQD) on the platelet aggregation induced by thrombin and its mechanism. METHODS: Platelet aggregation was analysed by turbidimetry. Cytosolic free calcium concentration ([Ca2+]i) was determined by Fura-2 fluorescence technique. Activity of Ca2+/PL dependent protein kinase C (PKC) was assayed by incubating PKC with histone III S and [gamma-32P]ATP. The cytoskeletal proteins were precipitated by Triton and separated by SDS-PAGE. RESULTS: DQD inhibited the platelet aggregation induced by thrombin (500 U/L), when DQD concentrations were 100, 200, and 400 mumol/L, the inhibition rates were 77%, 86%, and 82% respectively. DQD inhibited Ca2+ influx in platelets induced by thrombin (500 U/L) in the presence of extracellular Ca2+ 1 mmol/L in a concentration-dependent manner (10-80 mumol/L); DQD also had inhibitory effect on intracellular Ca2+ mobilization in the absence of extracellular Ca2+. DQD (10-160 mumol/L) inhibited the cytosolic Ca2+/PL dependent PKC from platelets in a concentration-dependent manner, but had no effect on membrane PKC. DQD (20-200 mumol/L) inhibited the actin polymerization induced by thrombin (500 U/L) in platelets in a concentration-dependent manner. CONCLUSION: DQD inhibited pig platelet aggregation induced by thrombin and its molecular mechanism was due to its inhibition of Ca2+ influx, intracellular Ca2+ mobilization, Ca2+/PL dependent PKC activity, and actin polymerization.