The effect of posture and of compression of the neck on excretion of electrolytes and glomerular filtration; further studies

Compression of the neck of the sitting subject caused increase in urinary sodium output without change in glomerular filtration (creatinine clearance) or apparent cardiac output (electrokymograph). The possible existence of an intracranial mechanism sensitive to alterations in volume of extracellular fluid and regulating the volume of extracellular fluid is suggested.

The effect of posture and of congestion of the head on sodium excretion in normal subjects

In healthy young subjects the sodium excretion is decidedly less in the sitting than in the recumbent posture. The difference can be partially overcome by compression of the neck in the sitting position. Some possible implications of these observations will be considered in the subsequent communications.