AJP - Renal Physiology, Vol 259, Issue 3 480-F484, Copyright © 1990 by American Physiological Society
Differential Na fluxes with artificial and native fluids in clip models of volume expansion
S. Reddy, C. Cochineas and A. Z. Gyory
Department of Medicine, University of Sydney, Australia.
Earlier we demonstrated significant differences in proximal tubular Na
transport inhibition during saline volume expansion (VE) depending on
whether artificial (AF) or native harvested tubular fluid (HTF) was used.
In the present experiments the shrinking-drop technique was used to measure
volume flux (Jv) in the early- and late-clip models of VE with AF
alternating with HTF. In early-clip rats, with AF, Jv (x 10(4)
mm3.mm-2.s-1) during the nonexpanded period was 2.92 +/- 0.105; during
subsequent VE, it was 2.20 +/- 0.180 and 1.97 +/- 0.149 with HTF (for the
latter two P greater than 0.3). In late-clip rats they were 2.83 +/- 0.135,
1.99 +/- 0.157, and 1.50 +/- 0.171 (for the latter two P less than 0.001),
respectively. With AF, transport was inhibited equally in both models
during VE. There were no significant differences in the electrolyte
composition of AF and HTF during shrinkage as measured by microprobe
analysis. The 47% inhibition of Jv with HTF but not AF during VE in the
late-clip but not the early-clip rats strongly implies the presence of
factors other than physical forces during VE, which inhibit proximal
tubular Na transport. Studies of tubular transport during VE need to be
performed using both AF and HTF.
