Abstract
Membrane transport processes are poorly developed in the kidney of the very preterm neonate resulting in reduced ability to acidify urine and increased Na+ loss. There are close homologies between the transport processes of the distal convoluted tubule and the L colon but little is known of the ontogeny of these processes. We have used non-equilibrium rectal dialysis to investigate rectal electrolyte transport in neonates of different gestational ages: 30-33 wks (A n=15), 34-36 wks (B n=14), 38-44 wks (C n=5), infants (D n=17) and older children (E n=19). Na+ absorption was highest in A (316±65 nmol/min/cm) and lowest in E (149±44, p<0.005). Plasma aldosterone was markedly elevated in A and B (7570±2500 pmol/l) compared to infant reference values (790±210, p<0.005). Cl− absorption paralleled Na+ absorption. HCO3− movement provides an indication of anion exchange and in A (59±14), B (26±30) and C (22±20)was absorbed but in D there was little net movement (3±24) and in E (11±16) net secretion.
These datashow that colonic, unlike renal, Na+ transport processes are efficient in the preterm neonate and that aldosterone is an important regulatory hormone. The colon is thus the major organ of Na+ conservation and the consequences of colonic surgery should be carefully considered. However, anion exchange seems to undergo similar developmental processes in both organs and this might explain the greater susceptibility to acidosis than hyponatraemia in the preterm neonate.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Jenkins, H., Fenton, T., Mcintosh, N. et al. 7. DEVELOPMENT OF EPITHELIAL ELECTROLYTE TRANSPORT PROCESSES IN EARLY CHILDHOOD. Pediatr Res 22, 97 (1987). https://doi.org/10.1203/00006450-198707000-00028
Issue Date:
DOI: https://doi.org/10.1203/00006450-198707000-00028