Wirkung von Aldosteron auf die Natrium-und Wasserresorption im proximalen Tubulus bei chronischer Kochsalzbelastung

✍ Scribed by Klaus O. Stumpe; Bruno Ochwadt

• Publisher: Springer
• Year: 1968
• Tongue: English
• Weight: 815 KB
• Volume: 300
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00362546

✦ Synopsis

Rats were kept on isotonic saline as drinking fluid for a period of 4 weeks. Glomerular filtration rate and proximal transit time of Lissamine green remained unchanged. The intrinsic reabsor~ptive capacity of the proximal tubular epithelium--measured by the "shrinking-droplet-method'--decreased significantly. As a result, fractional proximal reabsorption of sodium and water decreased from 51 to 38 per cent of the filtered load. Sodium excretion rose from 0.06 (controls) to 1,25 per cent of the filtered load. These changes were reversible by injection of d-aldosterone. The results were confirmed by measuring the TF/P ratio of inulin at the end of the proximal convolution.

The results indicate that in rats chronically loaded with salt, the inhibition of fractional proximal reabsorption is due to a decreased secretion of mineralocortieoids, and is the cause of the higher sodium excretion. Apparently, the decreased proximal reabsorption is partly compensated in more distal parts of the nephron.