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RENAL RESPONSE TO HYPOTONIC SALINE LOAD IN FETAL AND NEW‐BORN PIGS
Author(s) -
Alt J. M.,
Colenbrander B.,
MacDonald A. A.,
Forsling M. L.
Publication year - 1982
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.1982.sp002607
Subject(s) - saline , fetus , hypertonic saline , tonicity , biology , medicine , physiology , zoology , andrology , pregnancy , endocrinology , genetics
Kidney function has been studied in pig fetuses (105–109 d of gestation) and neonates (5–7 d old). Urine was collected by catheterization of the ureter. Inulin clearance, the excretion of electrolytes and the osmolality of urine and plasma were measured. In addition the response of the fetal neurohypophysis and fetal and neonatal kidney to a reduction of plasma osmolality was studied. The results show that the inulin clearance increases rapidly in the perinatal period, at a rate greater than would be expected from the gain in body weight. The re‐absorption of Na and K is well developed. The fractional sodium excretion in fetuses is 2% and is 0·1% in the new‐borns. The urine osmolality is high, probably due to high plasma lysine vasopressin levels persisting throughout the experiment. The infusion of hypotonic saline results in a significant decrease of plasma osmolality but only three out of nineteen animals showed an increase in urine flow. Although lysine vasopressin concentrations fell in some animals the urine stayed hyperosmotic as compared with plasma. The results show that fetuses and neonates may react to volume load but in the conditions of these experiments the regulation of plasma osmolality was inadequate.