Abstract

Background

The most profound effect of vasopressin on the kidney is to increase water reabsorption through V₂-receptor (V₂R) stimulation, but there are also data suggesting effects on calcium transport. To address this issue, we have established an isolated perfused kidney model with accurate pressure control, to directly study the effects of V₂R stimulation on kidney function, isolated from systemic effects.

Methods

The role of V₂R in renal calcium handling was studied in isolated rat kidneys using a new pressure control system that uses a calibration curve to compensate for the internal pressure drop up to the tip of the perfusion cannula.

Results

Kidneys subjected to V₂R stimulation using desmopressin (DDAVP) displayed stable osmolality and calcium reabsorption throughout the experiment, whereas kidneys not administered DDAVP exhibited a simultaneous fall in urine osmolality and calcium reabsorption. Epithelial sodium channel (ENaC) inhibition using amiloride resulted in a marked increase in potassium reabsorption along with decreased sodium reabsorption.

Conclusions

A stable isolated perfused kidney model with computer-controlled pressure regulation was developed, which retained key physiological functions. The preparation responds to pharmacological inhibition of ENaC channels and activation of V₂R. Using the model, the dynamic effects of V₂R stimulation on calcium handling and urine osmolality could be visualised. The study thereby provides evidence for a stimulatory role of V₂R in renal calcium reabsorption.

中文翻译：

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隔离大鼠肾脏中的电解质处理：血管加压素V2受体依赖性钙重吸收的证明

摘要

背景

加压素对肾脏的最深远影响是通过V _2-受体（V ₂ R）刺激增加水的重吸收，但也有数据表明对钙转运有影响。为了解决这个问题，我们建立了一个具有精确压力控制的孤立的灌注肾脏模型，以直接研究V ₂ R刺激对肾脏功能的影响（与全身作用无关）。

方法

使用新的压力控制系统对V ₂ R在离体大鼠肾脏中的作用进行了研究，该系统使用了一种新的压力控制系统，该系统使用校准曲线来补偿直至灌注套管尖端的内部压力下降。

结果

在整个实验过程中，使用去氨加压素（DDAVP）进行V ₂ R刺激的肾脏均表现出稳定的渗透压和钙重吸收，而未给予DDAVP的肾脏则表现出尿渗透压和钙重吸收同时下降。使用阿米洛利抑制上皮钠通道（ENaC）导致钾重吸收显着增加以及钠重吸收减少。

结论

建立了具有计算机控制的压力调节功能的稳定的隔离灌注肾脏模型，该模型保留了关键的生理功能。该制剂响应ENaC通道的药理学抑制和V ₂ R的激活。使用该模型，可以看到V ₂ R刺激对钙处理和尿渗透压的动态影响。因此，该研究提供了V ₂ R在肾钙重吸收中的刺激作用的证据。