Role fo AMP-activated protein kinase (AMPK) in diabetic nephropathy: change of tubuloglomerular feeedback and salt transport

amp活化蛋白激酶（AMPK）是一种丝氨酸-苏氨酸激酶，调节心脏和骨骼肌中脂肪酸ß-氧化、胆固醇合成、糖酵解和葡萄糖运输等多种代谢途径。AMPK被认为是一种能量传感器激酶，因为它以一种非常敏感的方式被细胞应激激活，从而消耗ATP或增加AMP/ATP比率。AMPK在哺乳动物肾脏中的作用尚不清楚。免疫组织化学和免疫荧光染色证实，活化AMPK在大鼠肾皮质增厚肢和黄斑致密细胞的顶膜以及集管细胞的基底外侧表面强烈表达。此外，高盐饮食处理的大鼠AMPK活性增加了25%，并且在黄斑致密细胞系中观察到AMPK的短暂激活，以响应渗透压的变化，这表明该激酶在控制小管盐重吸收和小管肾小球反馈反应中起作用。该项目的目的是阐明AMPK在控制肾血流动力学、小管盐运输和小管肾小球反馈中的作用。为此，我们将结合肾脏AMPK表达分析，在大鼠和转基因小鼠体内进行AMPK清除和微穿刺实验的药理抑制或激活。

AMP-activated protein kinase (AMPK) is a serine-threonine kinase that regulates many metabolic pathways including fatty acid ß-oxidation, cholesterol synthesis, glycolysis and glucose transport in heart and skeletal muscle. AMPK is considered as a energy sensor kinase since it is activated in a very sensitive manner by cellular stress that depletes ATP or increases AMP/ATP ratio. The role of AMPK in mamalian kidney is unknown. Immunohistochemical and immunofluorescence staining confirmed strong expression of activated AMPK in the apical membrance of cortical thick acending limb and macula densa cells as well as basolateral surface of the collecting duct cells of rat kidney. Furthermore, AMPK activity was increased by 25% in rats treated with high salt diet and a transient activation of AMPK was observed in a macula densa cell line in response to changes in osmolality suggesting a role for this kinase in the control of tubular salt reabsorption and tubuloglomerular feedback response. The aim of this project is to clarify the role of AMPK in control of renal hemodynamics, tubular salt transport and tubuloglomerular feedback. To this end, we will perform pharmacological inhibition or activation of AMPK in clearance and micropuncture experiments in rats and transgenic mice in vivo combined with analysis of renal AMPK expression.