Cruise J L
Department of Biology, College of St. Thomas, St. Paul, Minnesota 55105.
Dig Dis Sci. 1991 Apr;36(4):485-8. doi: 10.1007/BF01298880.
The alpha 1-adrenergic receptor mediates the effects of catecholamines on DNA synthesis, as observed in rat liver following a 2/3 partial hepatectomy and in serum-free primary cultures of adult rat hepatocytes exposed to epidermal growth factor. In vitro, norepinephrine action at this receptor heterologously down-regulates epidermal growth factor receptors. In vivo, the alpha 1 receptor's effect on DNA synthesis is restricted to early time points after partial hepatectomy. alpha 1 receptor binding capacity does not vary until 48 hr after liver resection (at which time binding is reduced), but an uncoupling of receptor binding from membrane phosphoinositide turnover occurs between 8 and 16 hr after partial hepatectomy. This change is preceded by a fall in membrane-associated ras p21 detected by radioimmunoassays (46% of control levels by 2 hr after partial hepatectomy). Whether this change represents a loss of p21 protein from membranes or a modification that results in a loss of immunoreactivity is not known.
α1 - 肾上腺素能受体介导儿茶酚胺对DNA合成的影响，这在2/3部分肝切除术后的大鼠肝脏以及暴露于表皮生长因子的成年大鼠肝细胞无血清原代培养物中均有观察到。在体外，去甲肾上腺素作用于该受体可异源性下调表皮生长因子受体。在体内，α1受体对DNA合成的影响仅限于部分肝切除术后的早期时间点。α1受体结合能力在肝切除术后48小时之前无变化（此时结合能力降低），但在部分肝切除术后8至16小时之间，受体结合与膜磷酸肌醇转换发生解偶联。这种变化之前，通过放射免疫测定法检测到膜相关的ras p21下降（部分肝切除术后2小时降至对照水平的46%）。这种变化是代表p21蛋白从膜上丢失还是导致免疫反应性丧失的修饰尚不清楚。
