PMID- 8825805
OWN - NLM
STAT- MEDLINE
DCOM- 19961203
LR  - 20190914
IS  - 0031-3998 (Print)
IS  - 0031-3998 (Linking)
VI  - 39
IP  - 2
DP  - 1996 Feb
TI  - Maturation of rabbit proximal convoluted tubule chloride permeability.
PG  - 308-12
AB  - Chloride transport in the rabbit proximal convoluted tubule (PCT) has components 
      of active, transcellular, and passive, paracellular transport. The preferential 
      reabsorption of bicarbonate and organic solutes by the early proximal tubule 
      leaves the luminal fluid with a higher chloride concentration than that in the 
      peritubular capillaries. Previous studies have suggested that solute permeability 
      of the paracellular pathway may be higher in the neonatal PCT and that the 
      neonatal proximal tubule reabsorbs solutes by passive mechanisms to a greater 
      extent than the adult segment. A higher chloride permeability would provide a 
      mechanism for the greater rate of passive NaCl transport by the neonatal proximal 
      tubule. The purpose of the present in vitro microperfusion study was to directly 
      examine the chloride permeability of neonatal and adult PCT. Superficial and 
      juxtamedullary, neonatal and adult PCT were perfused with a high chloride 
      perfusate without organic solutes, simulating late proximal tubular fluid, at 20 
      degrees C, and bathed in a serum-like albumin solution. Chloride concentrations 
      in the perfusate and the collected fluid were measured by electrometric 
      titration. Neonatal juxtamedullary PCT chloride permeability (PCl) was 
      significantly lower than adult juxtamedullary PCT PCl (0.15 +/- 0.25 x 10(-5) 
      cm/s versus 5.23 +/- 0.57 x 10(-5) cm/s, p < 0.001). The PCl of neonatal 
      superficial PCT was not different from that of adult superficial PCT (0.81 +/- 
      0.48 x 10(-5) cm/s versus 0.05 +/- 0.62 x 10(-5) cm/s). Thus, there is a 
      maturational increase in juxtamedullary PCT PCl, whereas superficial PCT PCl 
      remains very low. The passive diffusion of chloride in neonatal PCT is extremely 
      low and is not a mechanism to explain a higher rate of passive NaCl transport in 
      this segment.
FAU - Sheu, J N
AU  - Sheu JN
AD  - Department of Pediatrics, University of Texas Southwestern Medical Center at 
      Dallas 75235-9063, USA.
FAU - Baum, M
AU  - Baum M
FAU - Bajaj, G
AU  - Bajaj G
FAU - Quigley, R
AU  - Quigley R
LA  - eng
GR  - DK41612/DK/NIDDK NIH HHS/United States
GR  - K08-DK02232/DK/NIDDK NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Pediatr Res
JT  - Pediatric research
JID - 0100714
RN  - 0 (Chlorides)
SB  - IM
MH  - Animals
MH  - Animals, Newborn
MH  - Chlorides/*metabolism
MH  - Kidney Medulla/*metabolism
MH  - Kidney Tubules, Proximal/*metabolism
MH  - Rabbits
EDAT- 1996/02/01 00:00
MHDA- 1996/02/01 00:01
CRDT- 1996/02/01 00:00
PHST- 1996/02/01 00:00 [pubmed]
PHST- 1996/02/01 00:01 [medline]
PHST- 1996/02/01 00:00 [entrez]
AID - 10.1203/00006450-199602000-00020 [doi]
PST - ppublish
SO  - Pediatr Res. 1996 Feb;39(2):308-12. doi: 10.1203/00006450-199602000-00020.