Sampaio-Maia Benedita, Serrao Paula, Moura Manuela, Pestana Manuel
Institute of Pharmacology and Therapeutics, Porto, Portugal.
Nephrology (Carlton). 2006 Feb;11(1):63-7. doi: 10.1111/j.1440-1797.2006.00533.x.
The uninephrectomised and three-quarter nephrectomised (3/4nx) rats present dopamine-sensitive enhanced natriuresis. This is accompanied in uninephrectomised rats by a reduced jejunal Na(+),K(+)-ATPase activity with recovered sensitivity to inhibition by dopamine. The present study examined the jejunal Na(+),K(+)-ATPase activity and the role of dopamine in 3/4nx animals.
Fourteen days after surgery, the L-amino acid decarboxylase activity (AADC) activity, the enzyme responsible for the synthesis of dopamine, and the Na(+),K(+)-ATPase activity, were determined in jejunal epithelial cells from 3/4nx and Sham rats. In addition, the effect of dopamine (1 micromol/L) on jejunal Na(+),K(+)-ATPase activity was evaluated in both groups.
The 3/4nx rats presented a reduced AADC activity in jejunal epithelial cells (V(max) in nmol/mg prot/15 min, 142 +/- 6 vs 190 +/- 10, P < 0.05). In addition, the jejunal Na(+),K(+)-ATPase activity was increased in 3/4nx rats (Pi release in nmol/mg prot/min, 137 +/- 1 vs 122 +/- 2, P < 0.05). However, dopamine was unable to inhibit the Na(+),K(+)-ATPase activity in jejunal epithelial cells from both 3/4nx and Sham animals.
In contrast to uninephrectomy, the jejunal Na(+),K(+)-ATPase activity is increased in 3/4nx rats and is not sensitive to inhibition by dopamine.
单侧肾切除和四分之三肾切除（3/4nx）大鼠呈现出对多巴胺敏感的利钠增强现象。在单侧肾切除大鼠中，这伴随着空肠钠钾ATP酶活性降低，且对多巴胺抑制的敏感性恢复。本研究检测了3/4nx动物空肠钠钾ATP酶活性及多巴胺的作用。
术后14天，测定3/4nx大鼠和假手术大鼠空肠上皮细胞中负责多巴胺合成的L-氨基酸脱羧酶（AADC）活性以及钠钾ATP酶活性。此外，评估多巴胺（1微摩尔/升）对两组空肠钠钾ATP酶活性的影响。
3/4nx大鼠空肠上皮细胞中的AADC活性降低（最大反应速度，纳摩尔/毫克蛋白/15分钟，142±6对190±10，P<0.05）。此外，3/4nx大鼠空肠钠钾ATP酶活性升高（无机磷酸释放量，纳摩尔/毫克蛋白/分钟，137±1对122±2，P<0.05）。然而，多巴胺无法抑制3/4nx大鼠和假手术大鼠空肠上皮细胞中的钠钾ATP酶活性。
与单侧肾切除不同，3/4nx大鼠空肠钠钾ATP酶活性升高，且对多巴胺抑制不敏感。
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