容量性钙内流在大鼠脾脏α1B -肾上腺素能受体介导的对去氧肾上腺素收缩反应中的作用。
The role of capacitative Ca2+ influx in the alpha 1B-adrenoceptor-mediated contraction to phenylephrine of the rat spleen.
作者信息
Burt R P, Chapple C R, Marshall I
机构信息
Department of Pharmacology, University College London.
出版信息
Br J Pharmacol. 1995 Oct;116(4):2327-33. doi: 10.1111/j.1476-5381.1995.tb15073.x.
Abstract
- The mechanism of contraction to phenylephrine in the rat spleen (mediated via alpha 1B-adrenoceptors) has been studied in functional experiments. 2. The concentration-dependent contraction of the rat spleen to cumulative additions of phenylephrine (pD2 4.8 +/- 0.1) was not significantly reduced by the selective protein kinase C (PKC) inhibitor, calphostin C (10(-6)M) or potentiated by the DAG kinase inhibitor, R59022 (10(-6) M). 3. Contraction of the rat spleen in normal Krebs solution containing Ca2+ (2.5 mM) to a single concentration of phenylephrine (3 x 10(-4) M) produced a maximal response consisting of an initial phasic component and a more slowly developing tonic component. However in Ca(2+)-free Krebs solution (containing EGTA), phenylephrine (3 x 10(-4)M) produced only a phasic contraction which was reduced to 46 +/- 3% maximum response to phenylephrine in normal Krebs solution. 4. In some tissues after the contraction to phenylephrine (3 x 10(-4) M) in Ca(2+)-free Krebs solution (containing EGTA), the phenylephrine was washed out and the tissue was allowed to recover. After 2 h, upon addition of Ca2+ (2.5 mM) to the Krebs solution (EGTA now removed) a tonic contraction developed in the tissue (97 +/- 4% maximum response to phenylephrine). 5. Cyclopiazonic acid produced a tonic contraction of the rat spleen with a maximum effect at 10(-5) M (202 +/- 8% maximum response compared with that to phenylephrine). The contraction to CPA (10(-5) M) was reduced in Ca(2+)-free Krebs solution containing EGTA (30 +/- 4% of the maximum response to phenylephrine). One hour after the end of the contraction in Ca(2+)-free Krebs solution (EGTA now removed), upon addition of Ca2+ (2.5 mM) to the Krebs solution a tonic contraction developed in the tissue (263 +/- 12% maximum response to phenylephrine). 6 In Ca2+-free Krebs solution, after the spleen had been incubated with cyclopiazonic acid for 30 min,the subsequent contraction to phenylephrine (3 x 10-4 M) was reduced from 46+/-3% to 9+/-2%maximum response to phenylephrine.7 Cumulative contractions to phenylephrine and the contraction to cyclopiazonic acid (10-5 M) in the spleen were not significantly affected by nifedipine (10-6 M). The non-selective Ca2+channel blocker,SK&F 96365 (3 x 10-5 M) reduced the maximum response for the cumulative additions of phenylephrine to 35+/-1% and the contraction to CPA (10-5 M) from 202+/-8% to 108+/-8% maximum response to phenylephrine.8 The tyrosine kinase inhibitors genistein (3 x 10-5 M and tyrphostin 23 (10-4 M), reduced the maximum response to phenylephrine in the spleen to 51+/-4% and 44+/-5% respectively and the maximum contraction to cyclopiazonic acid (3 x 10-6 M) in the spleen from 132 +/- 6% to 82 +/-5% and 80 +/- 7% maximum response to phenylephrine respectively without affecting contractions to K+.9 In conclusion, these results are consistent with the contraction of the rat spleen to phenylephrine consisting of an initial phasic contraction due to release of intracellular Ca2+ and a larger tonic contraction due to capacitative Ca2+ influx through non-voltage-gated Ca2+ channels and which may involve a tyrosine kinase. This suggests that inositol triphosphate but not diacylglycerol is involved in the contraction.
摘要
- 通过功能实验研究了大鼠脾脏对去氧肾上腺素的收缩机制（经由α1B -肾上腺素能受体介导）。2. 大鼠脾脏对去氧肾上腺素累积添加的浓度依赖性收缩（pD2 4.8±0.1），并未被选择性蛋白激酶C（PKC）抑制剂钙磷蛋白C（10⁻⁶M）显著降低，也未被二酰甘油激酶抑制剂R59022（10⁻⁶M）增强。3. 在含有Ca²⁺（2.5 mM）的正常 Krebs 溶液中，大鼠脾脏对单一浓度去氧肾上腺素（3×10⁻⁴M）的收缩产生了最大反应，包括初始的相性成分和发展较为缓慢的紧张性成分。然而，在无 Ca²⁺的 Krebs 溶液（含有乙二醇双四乙酸）中，去氧肾上腺素（3×10⁻⁴M）仅产生相性收缩，该收缩在正常 Krebs 溶液中降至对去氧肾上腺素最大反应的46±3%。4. 在一些组织中，在无 Ca²⁺的 Krebs 溶液（含有乙二醇双四乙酸）中对去氧肾上腺素（3×10⁻⁴M）收缩后，将去氧肾上腺素洗脱，使组织恢复。2小时后，向 Krebs 溶液中添加 Ca²⁺（2.5 mM）（此时乙二醇双四乙酸已去除），组织中出现紧张性收缩（对去氧肾上腺素最大反应的97±4%）。5. 环匹阿尼酸使大鼠脾脏产生紧张性收缩，在10⁻⁵M时效果最大（与对去氧肾上腺素相比，最大反应为202±8%）。在含有乙二醇双四乙酸的无 Ca²⁺的 Krebs 溶液中，对环匹阿尼酸（10⁻⁵M）的收缩减少（为对去氧肾上腺素最大反应的30±4%）。在无 Ca²⁺的 Krebs 溶液中收缩结束1小时后（此时乙二醇双四乙酸已去除），向 Krebs 溶液中添加 Ca²⁺（2.5 mM），组织中出现紧张性收缩（对去氧肾上腺素最大反应的263±12%）。6. 在无 Ca²⁺的 Krebs 溶液中，脾脏用环匹阿尼酸孵育30分钟后，随后对去氧肾上腺素（3×10⁻⁴M）的收缩从对去氧肾上腺素最大反应的46±3%降至9±2%。7. 脾脏对去氧肾上腺素的累积收缩以及对环匹阿尼酸（10⁻⁵M）的收缩，未被硝苯地平（10⁻⁶M）显著影响。非选择性 Ca²⁺通道阻滞剂SK&F 96365（3×10⁻⁵M）将去氧肾上腺素累积添加的最大反应降低至35±1%，将对环匹阿尼酸（10⁻⁵M）的收缩从对去氧肾上腺素最大反应的202±8%降至108±8%。8. 酪氨酸激酶抑制剂染料木黄酮（3×10⁻⁵M）和 tyrphostin 23（10⁻⁴M）分别将脾脏对去氧肾上腺素的最大反应降低至51±4%和44±5%，将脾脏对环匹阿尼酸（3×10⁻⁶M）的最大收缩从对去氧肾上腺素最大反应的132±6%分别降至82±5%和80±7%，而不影响对钾离子的收缩。9. 总之，这些结果与大鼠脾脏对去氧肾上腺素的收缩一致，该收缩包括由于细胞内 Ca²⁺释放引起的初始相性收缩以及由于通过非电压门控 Ca²⁺通道的容量性 Ca²⁺内流引起的更大的紧张性收缩，并且可能涉及酪氨酸激酶。这表明肌醇三磷酸而非二酰甘油参与了收缩。
Zotero 插件