Garibotto G, Russo R, Franceschini R, Robaudo C, Saffioti S, Sofia A, Rolandi E, Deferrari G, Barreca T
Department of Internal Medicine, Genoa University, Genoa, Italy.
Biochem Biophys Res Commun. 1998 Jun 18;247(2):504-9. doi: 10.1006/bbrc.1998.8819.
To assess the individual role of splanchnic organs, kidney, and peripheral tissues on leptin metabolism, leptin exchange across the splanchnic bed, kidney, and leg has been evaluated by the arterio-venous technique in post-absorptive non-obese subjects. Leptin levels in the hepatic and renal veins were significantly lower (p < 0.001), while femoral vein levels were consistently greater (p < 0.05) than in the artery. The fractional extraction of leptin, namely the percentage of arterial leptin extracted, was greater in splanchnic organs (16%) than in the kidney (9.5%). Urinary excretion of leptin was undetectable in most subjects, indicating that leptin is degraded within the kidney. There was no correlation between fractional extraction of leptin and glomerular filtration rate, whereas leptin fractional extraction was directly related to renal plasma flow (p = 0.017). Renal leptin clearance was about 50% of the glomerular filtration rate. Our data demonstrate that both splanchnic organs and the kidney cooperate in the disposal of leptin, while peripheral tissues add significant amounts of leptin to the circulation. In non-obese subjects the contribution of the kidney to whole body clearance is no more than 50%. The removal of leptin by the kidney depends on renal plasma flow but not on glomerular filtration rate or filtered leptin.
为评估内脏器官、肾脏及外周组织在瘦素代谢中的个体作用，采用动静脉技术对吸收后非肥胖受试者的内脏床、肾脏及腿部的瘦素交换进行了评估。肝静脉和肾静脉中的瘦素水平显著较低（p < 0.001），而股静脉中的瘦素水平始终高于动脉中的水平（p < 0.05）。瘦素的分数提取率，即动脉中提取的瘦素百分比，在内脏器官中（16%）高于肾脏（9.5%）。大多数受试者的尿瘦素排泄量无法检测到，这表明瘦素在肾脏内被降解。瘦素的分数提取率与肾小球滤过率之间无相关性，而瘦素分数提取率与肾血浆流量直接相关（p = 0.017）。肾脏的瘦素清除率约为肾小球滤过率的50%。我们的数据表明，内脏器官和肾脏在瘦素的处理中相互协作，而外周组织则向循环中添加了大量瘦素。在非肥胖受试者中，肾脏对全身清除的贡献不超过50%。肾脏对瘦素的清除取决于肾血浆流量，而不取决于肾小球滤过率或滤过的瘦素。
