Vandenburgh H H, Karlisch P, Shansky J, Feldstein R
Department of Pathology, Brown University, Providence, Rhode Island 02906.
Am J Physiol. 1991 Mar;260(3 Pt 1):C475-84. doi: 10.1152/ajpcell.1991.260.3.C475.
Skeletal myofibers differentiated from primary avian myoblasts in tissue culture can be maintained in positive nitrogen balance in a defined serum-free medium for at least 6-7 days when embedded in a three-dimensional collagen gel matrix. Incubation of established myofiber cultures for 3-7 days with insulin (1 microM) or insulin-like growth factor I (IGF-I, 32 nM) stimulates both cell hyperplasia and myofiber hypertrophy. Mean myofiber diameter increases 71-98%. Insulin-like growth factor II stimulates cell hyperplasia but not myofiber hypertrophy. Cell growth results from a 42-62% increase in total protein synthesis and a 28-38% decrease in protein degradation. Myosin heavy-chain content increases 183-258% because of a 55% stimulation of myosin synthesis and 33-61% inhibition of degradation. Associated with myofiber hypertrophy is a 87-148% increase in the number of myofiber nuclei per unit myofiber length. The results indicate that insulin and IGF-I, but not IGF-II, can induce rapid myofiber hypertrophy in vitro, most likely by stimulating myoblast proliferation and/or fusion to established myofibers.
在组织培养中，从原代禽成肌细胞分化而来的骨骼肌肌纤维，当包埋在三维胶原凝胶基质中时，可在限定的无血清培养基中维持正氮平衡至少6 - 7天。用胰岛素（1微摩尔）或胰岛素样生长因子I（IGF - I，32纳摩尔）对已建立的肌纤维培养物进行3 - 7天的孵育，可刺激细胞增生和肌纤维肥大。平均肌纤维直径增加71 - 98%。胰岛素样生长因子II刺激细胞增生，但不刺激肌纤维肥大。细胞生长源于总蛋白合成增加42 - 62%以及蛋白降解减少28 - 38%。肌球蛋白重链含量增加183 - 258%，这是由于肌球蛋白合成受到55%的刺激以及降解受到33 - 61%的抑制。与肌纤维肥大相关的是每单位肌纤维长度的肌纤维核数量增加87 - 148%。结果表明，胰岛素和IGF - I而非IGF - II能够在体外诱导快速的肌纤维肥大，最有可能是通过刺激成肌细胞增殖和/或与已建立的肌纤维融合。
