Bonewitz R F, Foulkes E C, O'Flaherty E J, Hertzberg V S
Am J Physiol. 1983 Mar;244(3):G314-20. doi: 10.1152/ajpgi.1983.244.3.G314.
Effects of dexamethasone and adrenalectomy on the kinetics of jejunal 65Zn uptake and absorption were studied in the anesthetized adult rat. The jejunal lumen was perfused in situ with 5 mM glucose in 150 mM saline containing 65Zn and [14C]polyethylene glycol as volume marker. Over the 30-min perfusion period, the rate of net 65Zn removal from the perfusate was biexponential due to the establishment of a return flux to the lumen. An open two-compartment model satisfactorily describes these observations: (formula; see text) Dexamethasone (2 mg/kg ip 7 h before perfusion) increased k12 by 75% (P less than 0.0002) and decreased k20 by 45% (P less than 0.04). Both effects were independent of adrenalectomy. Mathematical simulations using the compartmental model and experimentally determined kinetic constants predicted that transfer of 65Zn into the body should be enhanced by adrenalectomy and retarded by dexamethasone administered to adrenalectomized rats. Dexamethasone and adrenalectomy thus differentially affect Zn uptake and absorption in this system, suggesting a possible adrenocortical hormone involvement in the regulation of Zn absorption. These changes are apparently not mediated via metallothionein.
在地塞米松和肾上腺切除术对成年麻醉大鼠空肠65Zn摄取和吸收动力学的影响的研究中，空肠腔在原位用含65Zn和[14C]聚乙二醇作为体积标记物的150 mM盐水中的5 mM葡萄糖进行灌注。在30分钟的灌注期内，由于建立了向肠腔的回流，从灌注液中净去除65Zn的速率呈双指数变化。一个开放的双室模型令人满意地描述了这些观察结果：（公式；见正文）地塞米松（灌注前7小时腹腔注射2 mg/kg）使k12增加75%（P小于0.0002），使k20降低45%（P小于0.04）。这两种作用均与肾上腺切除术无关。使用房室模型和实验确定的动力学常数进行的数学模拟预测，肾上腺切除术应增强65Zn向体内的转运，而对肾上腺切除大鼠给予地塞米松则会延迟这种转运。因此，地塞米松和肾上腺切除术对该系统中锌的摄取和吸收有不同影响，提示肾上腺皮质激素可能参与锌吸收的调节。这些变化显然不是通过金属硫蛋白介导的。
