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目的:观察多巴胺D3受体(D3受体)对大鼠肾脏近曲小管(RPT)上皮细胞多巴胺D4受体(D4受体)表达和功能的影响。方法:以Wistar-Kyoto(WKY)大鼠RPT上皮细胞为研究对象,利用免疫印迹法观察D3受体激动剂PDl28907刺激D3受体后D4受体表达的变化;采用哇巴因法测定Na+-K+-ATP酶(ATP为三磷酸腺苷)活性,观察D3受体激动剂PDl28907(10-7mol/L,24 h)预先作用后,D4受体激动剂PD168077(10-7mol/L,15 min)对Na+-K+-ATP酶活性的影响。同时,探讨D3受体激动剂PDl28907影响D4受体表达的作用机制。结果:D3受体激动剂PDl28907刺激可明显增强RPT上皮细胞中的D4受体蛋白表达,该作用呈时间与浓度依赖性关系。D3受体激动剂PDl28907对D4受体蛋白表达的增强作用可被D3受体特异性抑制剂U99194A(10-6mol/L)所阻断。磷脂酶C抑制剂U73122存在的情况下,D3受体激动剂PD128907刺激D3受体后对D4受体的促进表达效应受到显著抑制。与单用D4受体激动剂PD168077相比,在PDl28907(10-7mol/L,24 h)预先刺激的情况下,D4受体激动剂PD168077对Na+-K+-ATP酶活性的抑制作用有所增强。结论:D3受体对大鼠RPT上皮细胞上D4受体表达和功能具有增强作用,此作用可能通过磷脂酶C信号途径发挥影响。
Objective: To observe the effect of dopamine D3 receptor (D3 receptor) on the expression and function of dopamine D4 receptor (D4 receptor) in the proximal renal tubular epithelial cells (RPT) in rats. Methods: The Wistar-Kyoto (WKY) rat RPT epithelial cells were used as experimental objects. The expression of D4 receptor was measured by immunoblotting with D3 receptor agonist PD128907. The Î ± -K + ATPase (ATP as ATP) activity. The effect of D4 receptor agonist PD168077 (10-7mol / L, 15 min) on Na + - ATPase activity was observed after pretreatment with D3 receptor agonist PD128907 K + -ATP enzyme activity. At the same time, explore the mechanism of D3 receptor agonist PD128907 affecting D4 receptor expression. Results: D3 receptor agonist PD128907 stimulated the expression of D4 receptor protein in RPT epithelial cells in a concentration-dependent manner. D3 receptor agonist PDl28907 D4 receptor protein enhance the role of D3 receptor specific inhibitor U99194A (10-6mol / L) blocked. In the presence of phospholipase C inhibitor U73122, the effect of D3 receptor agonist PD128907 on D4 receptor stimulated D3 receptor was significantly inhibited. Compared with PD168077 alone, the inhibitory effect of PD168077 on Na + -K + -ATPase activity was enhanced under the pre-stimulation of PD129090 (10-7mol / L, 24 h) . CONCLUSION: D3 receptor can enhance the expression and function of D4 receptor on RPT epithelial cells in rats, and this effect may play an important role through phospholipase C signaling pathway.