Maturation of rabbit proximal straight tubule chloride/base
exchange.
Shah, Mehul, Raymond Quigley, and Michel Baum.
Department of Pediatrics and Internal Medicine, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75235-9063
APStracts 5:0021F, 1998.
The present in vitro microperfusion study compared the mechanism and
rates of NaCl transport in neonatal and adult rabbit proximal
straight tubules. In proximal straight tubules perfused with a late
proximal tubular fluid and bathed in a serum-like albumin solution,
the rate of volume absorption (JV) was 0.54+0.10 and 0.12+0.05
nl/mm(.min in adults and neonates, respectively (p<0.05). With the
addition of 10-5M bath ouabain, JV decreased to 0.27+0.07 and
-0.03+0.04 nl/mm(min in adult and neonatal tubules, respectively
(p<0.05), consistent with lower rates of active and passive NaCl
transport in the neonatal proximal straight tubule. The effect of
luminal sodium and chloride removal on intracellular pH (pHi ) was
used to assess the relative rates of Na+/H+ and Cl-/base exchange.
The rates of Na+/H+ and Cl-/base exchange were approximately five
-fold less in neonatal proximal straight tubules than adult tubules.
In both neonatal and adult proximal straight tubules the rate of Cl
-/base exchange was not affected by formate, bicarbonate, or cyanide
and acetazolamide, consistent with Cl-/OH- exchange. These data
demonstrate an increase in proximal straight tubule NaCl transport
during postnatal renal development.
Received 20 October 1997; accepted in final form 15 January 1998.
APS Manuscript Number F335-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 28 January 1998