Meidell R S, Sen A, Henderson S A, Slahetka M F, Chien K R
Am J Physiol. 1986 Nov;251(5 Pt 2):H1076-84. doi: 10.1152/ajpheart.1986.251.5.H1076.
The effects of adrenergic stimulation on the rates of protein synthesis, degradation, and accumulation were examined in primary cultures of neonatal rat heart cells. Treatment of myocardial cells with norepinephrine increased total cellular protein content and the rate of incorporation of radiolabeled tyrosine into trichloroacetic acid insoluble protein. alpha 1-Adrenergic, but not alpha 2- or beta-adrenergic blockade, inhibited these norepinephrine induced increases. The rate of protein synthesis estimated from the kinetics of equilibrium labeling and from combined equilibrium and pulse labeling was increased by norepinephrine stimulation, whereas protein degradation estimated by release of previously incorporated radiolabeled tyrosine or in pulse-chase experiments was unaffected. To determine whether alpha 1-adrenergic stimulation produced similar effects on the turnover of myofibrillar proteins, rates of synthesis and degradation were estimated for a myofibrillar-enriched protein fraction and for myosin heavy chain and actin. Norepinephrine treatment produced increases in the synthesis of myofibrillar protein without significantly altering degradation rates. These experiments suggest that alpha 1-adrenergic stimulation increases myocardial cell protein content by accelerating protein synthesis.
在新生大鼠心脏细胞的原代培养物中，研究了肾上腺素能刺激对蛋白质合成、降解和积累速率的影响。用去甲肾上腺素处理心肌细胞可增加细胞总蛋白含量以及放射性标记酪氨酸掺入三氯乙酸不溶性蛋白的速率。α1肾上腺素能阻断而非α2或β肾上腺素能阻断可抑制这些去甲肾上腺素诱导的增加。通过平衡标记动力学以及联合平衡和脉冲标记估计的蛋白质合成速率因去甲肾上腺素刺激而增加，而通过释放先前掺入的放射性标记酪氨酸或在脉冲追踪实验中估计的蛋白质降解则未受影响。为了确定α1肾上腺素能刺激是否对肌原纤维蛋白的周转产生类似影响，对富含肌原纤维的蛋白组分以及肌球蛋白重链和肌动蛋白的合成和降解速率进行了估计。去甲肾上腺素处理使肌原纤维蛋白的合成增加，而降解速率没有显著改变。这些实验表明，α1肾上腺素能刺激通过加速蛋白质合成增加心肌细胞蛋白含量。
