CONTROL OF PULMONARY VASCULAR SMOOTH-MUSCLE TONE BY SARCOPLASMIC-RETICULUM CA2+ PUMP BLOCKERS - THAPSIGARGIN AND CYCLOPIAZONIC ACID
CONTROL OF PULMONARY VASCULAR SMOOTH-MUSCLE TONE BY SARCOPLASMIC-RETICULUM CA2+ PUMP BLOCKERS - THAPSIGARGIN AND CYCLOPIAZONIC ACID
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DOI：
10.1007/bf00373982
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发表时间：
1995-03-01
影响因子：
4.5
通讯作者：
MARTHAN, R
中科院分区：
文献类型：
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作者：
DELAFUENTE, PG;SAVINEAU, JP;MARTHAN, R
研究了大鼠肺动脉机械活性的影响，探讨了肝素（TG）和环吡唑酸（CPA）的作用。在化学（β -escin）皮肤动脉条带中，在内部Ca2+储存（0.3 μ M游离Ca2+离子，8-10分钟）的加载过程之前和整个过程中，应用TG （0.1-1 μ M）或CPA （0.5-10 μ M）浓度依赖性地抑制了随后由去甲肾上腺素（NA, 10 μ M）或咖啡因（25 mM）诱导的收缩反应。在含Ca2+溶液（2.5 mM）中反复孵育10分钟，然后在na刺激前12分钟在无Ca2+溶液中孵育，TG和CPA不仅抑制了na诱导的收缩，而且增加了Ca2+暴露期间出现的张力。这两种现象以相似的时间进程发展。维拉帕米（10 μ M）和硝苯地平（1 μ M）不能拮抗Ca2+离子再入时的张力增加，但可以被La3+ (50 μ M)和Co2+ (1 mM)离子阻断。维拉帕米不敏感的TG（或CPA）诱导的收缩幅度依赖于外部[Ca2+][0.1-10 mM，一半最大效应浓度(EC(50)) = 0.85 mM]，不受外部[Na+]减少（从130到10 mM）的影响，也不受富含K+ (30-120 mM)溶液对条带去极化的影响。后一种条件下，在60和120 mM K+的存在下，分别观察到38 +/- 9%和83 +/- 4%的还原（n = 5）。酪氨酸激酶抑制剂染料木素（0.5-50 μ M）和tyrphostin （2-50 μ M）也能浓度依赖性地抑制这种收缩。在TG或CPA诱导的维拉帕米不敏感收缩中，Sr2+离子未能取代Ca2+离子（n = 4）。最后，TG （1 mu M）和CPA （10 mu M）没有改变剥皮条中pCa张力关系（n = 5）。这些结果表明，TG和CPA在大鼠肺动脉中的主要作用是阻止内部Ca2+储存的再填充。TG和CPA似乎也通过特定的维拉帕米不敏感途径促进Ca2+内流。该途径的生物物理和分子特征仍有待阐明，尽管它似乎涉及酪氨酸激酶活性。
The effect of thapsigargin (TG) and cyclopiazonic acid (CPA) on the mechanical activity of the rat pulmonary artery were investigated. In chemically (beta-escin)-skinned arterial strips, application of TG (0.1-1 mu M) or CPA (0.5-10 mu M) prior and throughout the loading procedure of the internal Ca2+ stores (0.3 mu M free Ca2+ ions for 8-10 min) concentration dependently inhibited the subsequent contractile response induced by noradrenaline (NA, 10 mu M) or caffeine (25 mM). In intact strips repeatedly incubated in a Ca2+-containing solution (2.5 mM for 10 min), followed by incubation in a Ca2+-free solution 12 min before NA-stimulation, TG and CPA not only inhibited the NA-induced contraction but also increased the tension which appeared during the exposure time to Ca2+. The two phenomena developed with similar time courses. The increase in tension during the readmission of Ca2+ ions was not antagonized by verapamil (10 mu M) or nifedipine (1 mu M) but was blocked by La3+ (50 mu M) and Co2+ (1 mM) ions. The amplitude of the verapamil-insensitive TG (or CPA)-induced contraction was dependent on the external [Ca2+][0.1-10 mM, concentration for half maximal effect (EC(50)) = 0.85 mM], not modified by the reduction of the external [Na+] (from 130 to 10 mM) and decreased by depolarization of the strip using K+-rich (30-120 mM) solutions. Under the latter condition, 38 +/- 9 and 83 +/- 4% reduction (n = 5) was observed in the presence of 60 and 120 mM K+ respectively. This contraction was also concentration dependently inhibited by the tyrosine kinase inhibitors genistein (0.5-50 mu M) and tyrphostin (2-50 mu M). Sr2+ ions, which contracted both depolarized intact and skinned strips, failed to replace Ca2+ ions in the verapamil-insensitive contraction induced by TG or CPA (n = 4). Finally, TG (1 mu M) and CPA (10 mu M) did not modify the pCa tension relationship in skinned strips (n = 5). These results show that the main action of TG and CPA in rat pulmonary artery is to prevent the refilling of the internal Ca2+ store. TG and CPA also seem to facilitate a Ca2+ influx through a specific verapamil-insensitive pathway. The biophysical and molecular characteristics of this pathway remain to be elucitated, although it appears to involve a tyrosine kinase activity.