Gupta M, Zak R
Department of Medicine, University of Chicago, Illinois 60637.
Am J Physiol. 1992 Mar;262(3 Pt 2):R346-9. doi: 10.1152/ajpregu.1992.262.3.R346.
Changes in myosin expression were studied after the removal of functional overload of skeletal and cardiac muscles. In the first set of experiments the chicken slow tonic anterior latissimus dorsi muscle was overloaded by placing a lead band over the wing. In the overloaded muscles the normal developmental progression toward elimination of slow myosin SM-1 was accelerated. No reexpression of SM-1 took place after weight removal. In the second set of experiments rat heart was overloaded by constriction of abdominal aorta. Isomyosin composition and the abundance of mRNA coding for alpha- and beta-myosin heavy chain (MHC) was determined. The overload resulted in downregulation of the alpha-MHC with corresponding upregulation of beta-MHC expression. Debanding resulted in the regression of hypertrophy and rapid return of alpha-MHC to normal values. In contrast, the recovery in beta-MHC expression was much slower and at 7 wk of debanding still remained substantially elevated.
在去除骨骼肌和心肌的功能性超负荷后，研究了肌球蛋白表达的变化。在第一组实验中，通过在鸡翼上放置铅带来使鸡的慢张力背阔肌超负荷。在超负荷的肌肉中，向消除慢肌球蛋白SM-1的正常发育进程加速。去除重量后，SM-1没有重新表达。在第二组实验中，通过腹主动脉缩窄使大鼠心脏超负荷。测定了同工型肌球蛋白组成以及编码α-和β-肌球蛋白重链（MHC）的mRNA丰度。超负荷导致α-MHC下调，同时β-MHC表达相应上调。去除束带导致肥大消退，α-MHC迅速恢复到正常值。相比之下，β-MHC表达的恢复要慢得多，在去除束带7周后仍显著升高。
