A PKA inhibitor
H-89 is a potent inhibitor of cyclic AMP-dependent protein kinase (protein kinase A) with IC50 of 48 nM and has weak inhibition on PKG, PKC, Casein Kinase, and others kinases.
H-89 inhibits protein kinase A, in competitive fashion against ATP. H-89 causes a dose-dependent inhibition of the forskolin-induced protein phosphorylation, with no decrease in intracellular cyclic AMP levels in PC12D cells. H-89 significantly inhibits the forskolin-induced neurite outgrowth from PC12D cells. H-89 (30 uM) inhibits significantly cAMP-dependent histone IIb phosphorylation activity in PC12D cell lysates[1]. H-89 (1-2 uM) significantly slows the repriming rate in rat skinned fibres, most likely due to it deleteriously affecting the T-system potential. H-89 (10-100 uM) inhibits net Ca2+ uptake by the SR and affectes the Ca32-sensitivity of the contractile apparatus in rat skinned fibres[2].
H-89 (0.2 mg/100g, i.p.) significantly increases seizure latency and threshold in PTZ-treated animals. H-89 (0.05, 0.2 mg/100 g, i.p.) prevents the epileptogenic activity of bucladesine (300 nM) with significant increase of seizure latency and seizure threshold[3].
H-89是环磷酸依赖性蛋白激酶（蛋白激酶A）的强效抑制剂，IC50为48 nM，对PKG、PKC、Casein Kinase和其他激酶的抑制作用较弱。
H-89以竞争性方式抑制蛋白激酶A，对ATP敏感。H-89导致剂量依赖性抑制丙酮肟诱导的蛋白磷酸化，在PC12D细胞中，细胞内环磷酸腺苷水平无明显下降。H-89显著抑制丙酮肟诱导的PC12D细胞神经突起生长。H-89（30微米）显著抑制PC12D细胞裂解液中cAMP依赖性的histone IIb磷酸化活性[1]。H-89（1-2微米）显著减缓大鼠剥离纤维的再兴奋速率，最可能是由于其对T系统电位的有害影响。H-89（10-100微米）抑制大鼠剥离纤维的SR净Ca2+吸收，影响肌原纤维的Ca32+敏感性[2]。
H-89（0.2毫克/100克，i.p.）显著增加PTZ处理动物的癫痫潜伏期和阈值。H-89（0.05、0.2毫克/100克，i.p.）预防了Bucladesine（300纳摩尔）的癫痫活性，显著增加了癫痫潜伏期和癫痫阈值[3]。
参考文献:
[1]. Chijiwa T, et al. Inhibition of forskolin-induced neurite outgrowth and protein phosphorylation by a newly synthesized selective inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), of PC12D
[2]. Blazev R, et al. Effects of the PKA inhibitor H-89 on excitation-contraction coupling in skinned and intact skeletal muscle fibres. J Muscle Res Cell Motil. 2001;22(3):277-86.
[3]. Hosseini-Zare MS, et al. Effects of pentoxifylline and H-89 on epileptogenic activity of bucladesine in pentylenetetrazol-treated mice. Eur J Pharmacol. 2011 Nov 30;670(2-3):464-70.
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Kinase experiment: |
Kinase activities are assayed at 30°C for 2-5 min by measuring the transfer of 32P from [γ-32P]ATP to substrates. The reaction is terminated by adding 1 mL of 20% trichloroacetic acid, following the addition of 100 μg of bovine serum albumin as a carrier protein. The sample is centrifuged at 3000 rpm for 10 min, the pellet is resuspended in 5% trichloroacetic acid solution, the final pellet is dissolved in 1 mL of 1 N NaOH and the radioactivity is measured in a liquid scintillation counter. |
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Cell experiment: |
After 48 h in culture, PCl2D cells are cultured in test medium containing 30 μM H-89 for 1 h and then exposed to fresh medium that contained both 10 μM forskolin and 30 μM H-89. Cells are scraped off with a rubber policeman and sonicated in the presence of 0.5 mL of 6% trichloroacetic acid. To extract trichloroacetic acid, 2 mL of petroleum ether is added, the preparation mixed and centrifuged at 3000 rpm for 10 min. After aspiration of the upper layer, the residue sample solution is used for determination. |
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Animal experiment: |
Male albino mice weighing 20-25 g are obtained. Pentoxifylline (25, 50, 100 mg/kg), bucladesine (50, 100, 300 nM/mouse) and H-89 (0.05, 0.1, 0.2 mg/100 g) are administered intraperitoneally (i.p.) 30 min before intravenous (i.v.) infusion of PTZ. In combination groups, the first and second components are injected 45 and 30 min before PTZ infusion. In all groups, the respective control animalsreceive an appropriate volume of vehicle. For the i.v. infusion, the needle is inserted into the lateral tail vein, fixed to the tail vein by a narrow piece of adhesive tape, and the animal is allowed to move freely. PTZ solution is infused at a concentration rate of 1 mL/min. |
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参考文献: [1]. Chijiwa T, et al. Inhibition of forskolin-induced neurite outgrowth and protein phosphorylation by a newly synthesized selective inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), of PC12D pheochromocytoma cells. J Biol Chem. 1990 Mar 25;265(9):5267-72. |
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