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PERINATAL DEVELOPMENT OF TUBULAR FUNCTION IN THE PIG
Author(s) -
Alt J. M.,
Colenbrander B.,
Forsling M. L.,
MacDonald A. A.
Publication year - 1984
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1984.sp002861
Subject(s) - function (biology) , biology , microbiology and biotechnology
Renal tubular function has been studied in pig fetuses of 105–112 d gestational age in new‐born pigs 5–9 d old. The experiments were performed on anaesthetized animals, urines being collected by inserting a catheter into one ureter of the animal under study. The glomerular filtration rate was estimated and plasma concentrations and urinary excretion of the following substances were measured: sodium, potassium, calcium, ammonia, urea, phosphate, glucose, fructose, creatinine, protein and exogenous 4‐aminohippuric acid, and inulin. The reabsorption of water was considered in relation to the plasma vasopressin values. New‐born pigs were loaded with glucose and fructose in order to determine the maximal tubular transport rate of these substances. Significant changes at birth occur in only a few functions of the tubulus system. Following delivery, major changes are: (1) the increased reabsorption of sodium and water which is probably the most important adaptation to extra‐uterine life; (2) an apparent increasing impermeability of the tubular epithelium for creatinine, and (3) the direction of transport of fructose, which is reabsorbed by fetuses whereas neonates demonstrate a net secretion. Glucose and fructose are transported by different mechanisms. The experiments with fructose‐loaded piglets demonstrate that there are at least two transport mechanisms for fructose: reabsorption — either passive or active ‐ and secretion. The factors causing a shifting from one mechanism to the other are not yet known.