Maruyama Y, Sakai Y, Nobe K, Momose K
Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Life Sci. 1999;64(21):1933-40. doi: 10.1016/s0024-3205(99)00138-1.
Contractile responses to carbachol (CCh), protein kinase C (PKC) activity and distribution of PKC isoforms in subcellular fractions isolated from gastric antrum smooth muscle of control and streptozotocin (STZ)-induced diabetic rats were examined. CCh induced concentration-dependent contraction in antrum smooth muscle from controls and diabetics, and this contraction was significantly greater in diabetics than in controls. In diabetics, the PKC activity in the nucleus fraction was significantly decreased by about 63% in the resting condition and that in the cytosol fraction was significantly increased by about 135% after the treatment with 10 microM CCh for 10 min compared to controls. Immunoblot analysis showed that 8 PKC isoforms (-alpha, -beta, -gamma, -delta, -epsilon, -zeta, -iota, -lambda) were expressed in rat antrum smooth muscle. The PKC-beta isoform was significantly decreased by about 47% in the nucleus fraction in the resting condition in diabetics compared to controls. The nucleus, cytosol and membrane fractions of this isoform were decreased in controls after the treatment with 10 microM CCh for 10 min whereas these fractions were unchanged in diabetics. The PKC-epsilon significantly increased by about 219% in the cytosol fraction of diabetics in the resting condition, but the distribution of this isoform was unchanged in controls and diabetics after the treatment with 10 microM CCh for 10 min. Results suggest that the diversity of PKC isoform-specific distribution and translocation may be related to abnormal contractility and intracellular signal transduction through the PKC pathway in diabetics.
研究了对照大鼠和链脲佐菌素（STZ）诱导的糖尿病大鼠胃窦平滑肌分离的亚细胞组分中对卡巴胆碱（CCh）的收缩反应、蛋白激酶C（PKC）活性及PKC亚型的分布。CCh在对照和糖尿病大鼠的胃窦平滑肌中诱导浓度依赖性收缩，且糖尿病大鼠的这种收缩明显大于对照大鼠。在糖尿病大鼠中，与对照相比，静息状态下细胞核组分中的PKC活性显著降低约63%，用10μM CCh处理10分钟后，胞质溶胶组分中的PKC活性显著增加约135%。免疫印迹分析表明，8种PKC亚型（-α、-β、-γ、-δ、-ε、-ζ、-ι、-λ）在大鼠胃窦平滑肌中表达。与对照相比，糖尿病大鼠静息状态下细胞核组分中的PKC-β亚型显著降低约47%。用10μM CCh处理10分钟后，对照大鼠中该亚型的细胞核、胞质溶胶和膜组分减少，而糖尿病大鼠中这些组分未改变。糖尿病大鼠静息状态下胞质溶胶组分中的PKC-ε显著增加约219%，但用10μM CCh处理10分钟后，对照和糖尿病大鼠中该亚型的分布未改变。结果表明，PKC亚型特异性分布和易位的多样性可能与糖尿病大鼠异常的收缩性及通过PKC途径的细胞内信号转导有关。
