Glomerular protein separation as a mechanism for powering renal concentrating processes.
Various models have been proposed to explain the urine concentrating mechanism in mammals, however uncertainty remains regarding the origin of the energy required for the production of concentrated urine. We propose a novel mechanism for concentrating urine. We postulate that the energy for the concentrating process is derived from the osmotic potentials generated by the separation of afferent blood into protein-rich efferent blood and protein-deplete filtrate. These two streams run in mutual juxtaposition along the length of the nephron and are thus suitably arranged to provide the osmotic potential to concentrate the urine. The proposed model is able to qualitatively explain the production of various urine concentrations under different clinical conditions. An approach to testing the feasibility of the hypothesis is proposed.
Biomedical Engineering Research Group in the School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa. Electronic address: robyn.letts@wits.ac.za.
Robyn F R
RF
Letts
Biomedical Engineering Research Group in the School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa.
David M
DM
Rubin
MaPS, University of South Africa, South Africa.
Robert H
RH
Louw
MaPS, University of South Africa, South Africa.
Diane
D
Hildebrandt
D001798:Blood Proteins / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D060730:Glomerular Filtration Barrier / Q000502:physiology*; D006801:Humans; D007671:Kidney Concentrating Ability / Q000502:physiology*; D008954:Models, Biological; D065667:Renal Elimination / Q000502:physiology*
D001798:Blood Proteins