Postnatal Plasma Concentration and Urinary Excretion of Na and K in the Rat

Abstract

Summary

Rats show a critical period in electrolyte balance at around 40 days of age. PN_Na and U_NaV increase abruptly and U_K V falls at this time. P_K shows a continuous decrease over the age ranges studied. Hematocrit shows a hyperbolic increase. In metabolic studies, urinary Na/K shows a significant increase at the same critical period.