Concentration-dependent sodium chloride transport as the signal in feedback control of glomerular filtration rate.

There is good evidence that the initial step leading to a feedback response is the concentration-dependent active transport of sodium chloride across the macula densa cells. This may lead to changes in sodium chloride concentration or tonicity in the small and relatively unstirred compartment of the juxtaglomerular interstitium or to changes in the concentration of transport-related compounds or metabolites. We assume that the Goormaghtigh cells act as receptor cells that transform such compositional changes into a signal propagating to the glomerular vascular elements.