AJP - Renal Physiology, Vol 252, Issue 6 1042-F1047, Copyright © 1987 by American Physiological Society
Role of basolateral cell membranes in organic solute reabsorption in rabbit kidneys
E. C. Foulkes
The present work explores the contributions of basolateral carrier systems
in tubular reabsorption of organic solutes. Reabsorption of sugars and
amino acids, as previously shown, can be represented by a three-compartment
linear model that predicts that 1) if basolateral transport contributes to
sugar reabsorption, alpha-methylglucoside reabsorption compared with that
of glucose should be characterized by a longer transepithelial transit time
(TET) and a correspondingly increased cellular transport pool (S), and 2)
saturation of basolateral amino acid carriers, or presence of competing
amino acids or other basolateral transport inhibitors, should prolong TET
of a test amino acid, and increase S above the expected value. Both
predictions were fully confirmed. Heavy metal intoxication not only
inhibits transport of amino acids at the brush border, but also prolongs
their TET and increases the size of S for a given reabsorbed load.
Basolateral extrusion of amino acids is more sensitive to metals than is
uptake across the brush border. Although basolateral carriers accelerate
return of reabsorbed solute to blood, their contribution to reabsorption
does not seem to be mandatory.
