AJP - Renal Physiology, Vol 260, Issue 4 549-F554, Copyright © 1991 by American Physiological Society
Charge selectivity in kidney ultrafiltration is associated with glomerular uptake of transport probes
M. Tay, W. D. Comper and A. K. Singh
Biochemistry Department, Monash University, Clayton, Victoria, Australia.
The isolated perfused kidney exhibits substantial charge selectivity, as in
vivo, in relation to fractional clearance of [3H]dextran sulfate and
[3H]dextran. When cycloheximide is present in perfusate, fractional
clearance of dextran sulfate is increased and proteinuria becomes
significant, but glomerular filtration rate remains essentially unchanged
compared with control. The possible role of cells in affecting
transglomerular transport was demonstrated when isolated glomeruli from
control perfused kidneys showed a very significant resident concentration
of [3H]dextran sulfate and [3H]albumin, whereas there was no corresponding
accumulation of [3H]dextran or [3H]inulin. Glomerular concentration of
dextran sulfate and albumin was significantly reduced by cycloheximide.
Kinetics of uptake and release of glomerular dextran sulfate indicated that
it had a half-life of glomerular residence of approximately 2-3 min and
that this half-life was considerably extended in the presence of
cycloheximide. The half-life for glomerular residence of albumin was in the
range of 30-40 min. The conclusion from this work is that glomerular charge
selectivity for dextran sulfate could be quantitatively rationalized on the
basis of transient uptake and release by glomerular cells.
