MERCURY IN CHLORIDE TRANSPORT IN SHARK RECTAL GLAND & RABBIT THICK ASCENDING LIMB

这项建议的目的是研究 汞对氯化物转运上皮细胞转运的毒性作用。 汞抑制鲨鱼直肠腺和直肠腺中氯的运输 哺乳动物粗大的升肢及其作用机制 行动的方式是未知的。在拟议的一组实验中，我们将研究 有机汞和无机汞对氯离子迁移的影响 在鲨鱼的直肠腺上，并将其与厚厚的上升中的进行比较 亨勒环的分支。 汞、汞(包括无机汞和汞)的抑制机理 有机的)或由直肠腺或直肠腺转运氯化物的任何化合物 粗大的上升肢可以参照我们现在的情况进行评估 对这些细胞运输的理解。抑制作用是 可能存在于五个不同的位置：1)氯进入的位置 细胞，Na-K-2CI载体；2)用 从而降低了钠、氯化物进入的驱动力 和钾通过共转运蛋白；3)抑制细胞代谢 导致ATP不足，无法为泵提供动力；4)抑制 氯化物在根尖膜上通过根尖的缩小而退出 氯化物的膜电导；5)钾循环的抑制 通过钾传导途径。这些可能性可以是 结合使用特定的转运抑制剂和 水星。汞抑制氯离子转运的相加作用 在这些转运步骤的特定抑制剂的存在下 建议一个不同于特定抑制剂的作用部位。 因为我们在回应中发现了意想不到的显著差异 这两种上皮细胞由无机汞和有机汞组成，我们认为 这种比较方法将特别富有成效。我们会 研究汞的作用机制和细胞部位。 测定其在离体灌流直肠腺中的作用 直肠腺小管、直肠腺膜泡、直肠腺血浆 膜，厚厚的升肢细胞，厚厚的升肢小泡， 升肢质膜较厚。具体来说，我们将检查 汞与质膜和胞质蛋白结合的影响 汞对氯化物共转运体的作用，钾的外流， 氯电导及其对运输相关酶的影响。

The intent of this proposal is to study the mechanism of action of the toxic effect of mercury on transport by chloride transporting epithelia. Mercury inhibits chloride transport in both the shark rectal gland and the mammalian thick ascending limb but its mechanism of action mechanism of action is unknown. In the proposed set of experiments we will study the effect of organic and inorganic mercury on the transport of chloride by the shark rectal gland and compare it with that in the thick ascending limb of the loop of Henle. The mechanism of the inhibition of mercury, mercurial (both inorganic and organic) or of any compound on chloride transport by the rectal gland or the thick ascending limb can be evaluated with reference to our present understanding of transport by these cells. Inhibitory effects are possible at five different sites: 1) The site of entry of chloride into the cell, the Na-K-2CI carrier; 2) Inhibition of Na-K-ATPase with the resulting reduction in the driving force for entry of sodium, chloride and potassium via the cotransporter; 3) Inhibition of cellular metabolism resulting in insufficient ATP to power the pump; 4) Inhibition of the exit of chloride at the apical membrane by a reduction in the apical membrane conductance for chloride; 5) inhibition of potassium recycling through the potassium conductive pathway. These possibilities can be distinguished using specific transport inhibitors in combination with mercury. An additive effect of mercurial to inhibit chloride transport in the presence of specific inhibitors of these transport steps will suggest a site of action of distinct from that of the specific inhibitor. Because we have found unexpected and striking differences in the response of these two epithelia to inorganic and organic mercurial, we believe that the comparative approach will be particularly fruitful. We will examine the mechanism and the cellular site of action of mercury by determining its effect in the isolated perfused rectal gland, isolated rectal gland tubules, rectal gland membrane vesicles, rectal gland plasma membranes, thick ascending limb cells, thick ascending limb vesicles, thick ascending limb plasma membranes. Specifically we will examine the binding of mercury by plasma membranes and cytosolic proteins; the effect of mercury on the chloride cotransporter, the efflux of potassium, the chloride conductance, and its effect on transport related enzymes.