Ruiz-Sanchez Esau, O'Donnell Michael J
Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1, Canada.
J Exp Biol. 2007 Jul;210(Pt 14):2464-71. doi: 10.1242/jeb.003152.
The effects of chronic exposure to dietary salicylate on elimination and renal excretion of salicylate by D. melanogaster larvae were evaluated using salicylate-selective microelectrodes. Larvae chronically exposed to dietary salicylate showed 25% less salicylate in the haemolymph compared to the control group after feeding on a salicylate-enriched diet. By 1 h after transfer to a salicylate-free diet the levels of salicylate in the haemolymph of larvae raised on dietary salicylate were 46% lower than in the control group. Salicylate flux increased dramatically across Malpighian tubules but not across midgut or hindgut isolated from larvae chronically exposed to dietary salicylate, relative to the control group. Malpighian tubules isolated from experimental larvae showed a 4.7-fold increase in Kt and a nearly 5-fold increase in Jmax relative to the control. These changes in salicylate transport were accompanied by a 3.2-fold increase in fluid secretion rate. Moreover, the high rates of fluid secretion by the Malpighian tubules isolated from experimental larvae were stimulated 2.1-fold and 2.8-fold when tubules were challenged with 1 mmol l(-1) cAMP and 10 micromol l(-1) leucokinin I, respectively. Taken together, these results indicate that chronic exposure of D. melanogaster larvae to dietary salicylate alters elimination of such toxins from the haemolymph and increases the basal rate of fluid secretion and excretion of salicylate by the Malpighian tubules.
使用水杨酸盐选择性微电极评估了长期饮食摄入水杨酸盐对黑腹果蝇幼虫水杨酸盐消除和肾脏排泄的影响。与对照组相比，长期饮食摄入水杨酸盐的幼虫在喂食富含水杨酸盐的食物后，其血淋巴中的水杨酸盐含量低25%。在转移到不含水杨酸盐的食物1小时后，以饮食水杨酸盐饲养的幼虫血淋巴中的水杨酸盐水平比对照组低46%。相对于对照组，从长期饮食摄入水杨酸盐的幼虫分离出的马氏管中水杨酸盐通量显著增加，但从中肠或后肠分离出的通量没有增加。与对照组相比，从实验幼虫分离出的马氏管的转运体Kt增加了4.7倍，最大转运速率Jmax增加了近5倍。水杨酸盐转运的这些变化伴随着液体分泌速率增加3.2倍。此外，当用1 mmol l(-1) cAMP和10 micromol l(-1) 激肽释放酶I分别刺激从实验幼虫分离出的马氏管时，其高液体分泌速率分别提高了2.1倍和2.8倍。综上所述，这些结果表明，黑腹果蝇幼虫长期饮食摄入水杨酸盐会改变血淋巴中此类毒素的消除，并增加马氏管液体分泌和水杨酸盐排泄的基础速率。
