Alpha-adrenergic preservation of myocardial pH during ischemia is PKC isoform dependent.
Alpha-adrenergic preservation of myocardial pH during ischemia is PKC isoform dependent.
复制标题
缺血期间心肌 pH 值的α-肾上腺素能保持是 PKC 异构体依赖性的。
DOI：
10.1006/jsre.1996.0269
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Bannerjee,A
中科院分区：
文献类型：
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作者：
Rehring,TF;Friese,RS;Cleveland,JC;Meng,X;Robertson,FG;Harken,AH;Bannerjee,A
缺血性心脏病患者α-肾上腺素能刺激应直观施加破坏性应激。然而，在心肌缺血前，治疗性α - 1肾上腺素能受体介导的心脏适应可保护心室机械功能，促进电生理稳定性，并保持心肌细胞活力。在预期的心脏缺血损伤之前，α1-肾上腺素能预处理通过蛋白激酶C-(PKC)依赖机制减轻缺血性心肌酸中毒。α1肾上腺素能受体可以通过二酰基甘油（DAG）直接刺激钙依赖性的nPKC异构体，或通过三磷酸肌醇释放细胞内钙间接刺激钙依赖性的cPKC异构体（IP3）。我们假设缺血性酸中毒的α1-肾上腺素能限制是由钙依赖性PKC亚型家族介导的。[31P] α - 1肾上腺素能刺激[苯肾上腺素（PE） 50 μM， 2 min]大鼠离体缓冲灌注心脏核磁共振波谱；PKC阻断物[chelerythrine chloride， （Chel） 20 μM]；或在缺血前10分钟给予硬脂酰-花生四烯醇甘油（SAG， DAG类似物，100 μM， 2分钟）。对照心脏在常温条件下灌注20分钟。然后，所有心脏进行全身缺血（20分钟，37.5°C）。连续记录静息压（DP）和心率。ph是由无机磷酸盐的化学位移得到的。利用免疫组织化学染色来描绘每种刺激建立的特定PKC谱的易位和激活谱。缺血前α1-肾上腺素能刺激能明显减弱持续常温缺血时心肌细胞氢离子积累（6.90±0.13 vs对照组6.54±0.10；P< 0.05）。一般PKC抑制消除了这种影响（缺血末pH为6.17±0.10；与对照组和PE相比P< 0.05）。选择性nPKC刺激后，缺血性酸中毒没有减轻（SAG, 6.48±0.08；NS vs对照组）。心肌细胞免疫组化染色显示，在钙依赖性PKC （SAG）组中，钙依赖性PKC- ε异构体发生了易位，但对α1-肾上腺素能刺激没有反应。结果表明：(1)α1-肾上腺素能刺激限制缺血性酸中毒，(2)α1-肾上腺素能刺激的缺血性酸中毒衰减依赖于PKC， (3) SAG直接刺激nPKC不限制缺血性酸中毒，(4)SAG刺激nPKC- ε亚型激活，而α1-肾上腺素能刺激没有。我们得出结论，α1-肾上腺素能刺激通过cpkc依赖机制限制缺血性酸中毒，受体刺激激活IP3臂抑制PKC-御柱，从而限制缺血性酸中毒。
α-adrenergic stimulation of patients with ischemic heart disease should intuitively impose a destructive stress. However, therapeutic α1-adrenergic receptor mediated cardioadaptation prior to myocardial ischemia protects ventricular mechanical function, promotes electrophysiologic stability, and preserves myocyte viability. Prior to an anticipated cardiac ischemic insult, α1-adrenergic preconditioning attenuates ischemic myocardial acidosis by a protein kinase C-(PKC) dependent mechanism. The α1-adrenoceptor can directly stimulate calcium-independent nPKC isoforms via diacylglycerol (DAG) or indirectly stimulate calcium-dependent cPKC isoforms through the release of intracellular calcium via inositol triphosphate, (IP3). We hypothesized that α1-adrenergic limitation of ischemic acidosis is mediated by the family of calcium-dependent PKC isoforms. [31P]NMR spectra were obtained in isolated, buffer perfused rat hearts treated with α1-adrenergic stimulation [phenylephrine (PE) 50 μM, 2 min]; PKC blockade [chelerythrine chloride, (Chel) 20 μM]; or stearoyl-arachidonoyl glycerol (SAG, a DAG analogue, 100 μM, 2 min) administered 10 min prior to ischemia. Control hearts were perfused under normoxic conditions for 20 min. All hearts were then subjected to global ischemia (20 min, 37.5°C). Developed pressure (DP) and heart rate were recorded continuously. pHiwas obtained from chemical shift of inorganic phosphate. Immunohistochemical staining was utilized to delineate the translocation and activation profiles of specific PKC profiles established with each stimulus. Pre-ischemic α1-adrenergic stimulation did attenuate the myocellular hydrogen ion accumulation during sustained normothermic ischemia (6.90 ± 0.13 vs control 6.54 ± 0.10;P< 0.05). General PKC inhibition abrogated this effect (end-ischemic pH 6.17 ± 0.10;P< 0.05 vs control and PE). Ischemic acidosis was not attenuated following selective nPKC stimulation (SAG, 6.48 ± 0.08; NS vs control). Myocellular immunohistochemical staining revealed translocation of the calcium-independent PKC-ϵ isoform in the calcium-dependent PKC (SAG) group, but not in response to α1-adrenergic stimulation. The results suggest that (1) α1-adrenoceptor stimulation limits ischemic acidosis, (2) α1-adrenergic stimulated attenuation of ischemic acidosis is PKC dependent, (3) direct nPKC stimulation with SAG does not limit ischemic acidosis, and (4) SAG stimulates nPKC-ϵ isoform activation where α1-adrenergic stimulation does not. We conclude that α1-adrenergic stimulation limits ischemic acidosis by a cPKC-dependent mechanism and that the mobilization of the IP3 arm by receptor stimuli suppresses PKC-ϵ thus permitting the limitation of ischemic acidosis.