Development of renal potassium excretion capacity in the neonatal rat

Naohiko Anzai, Yoshiro Suzuki, Mariko Nishikitani, Ibuki Izumida-Moriguchi, Asako Kokubo, Katsumasa Kawahara

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Abstract

We investigated the capacity of newborn rats to excrete an acute potassium load to understand the development of a renal potassium excretion system. Three groups of the rats (7-14d) were used to collect urine periodically over 6 h after oral infusion of potassium: control (no potassium loading) and low- and high-potassium-loaded rats. In the low-potassium-loaded group, infused with about 0.6 μEq of potassium chloride/g body wt., the rate of renal potassium excretion increased from 0.08±0.02 (7d) to 0.13±0.02 (10d) and 0.21±0.03 (14d) μEq/h/g body wt. The high-potassium-loaded rats (1.52.81μEq/g body wt. potassium load) excreted potassium at a higher rate of 0.18±0.05 (7d), 0.30±0.02 (10d), and 0.45±0.10 (14d) μEq/h/g body wt. They excreted 77% (7d), 76% (10d), and 95% (14 d) of the potassium load. These values were much larger than the rate of 0.026 μEq/h/g body wt. of the control rats and of 0.08 μEq/h/g body wt., a mean potassium excretion rate during development from 7 to 14d calculated from the data in the previous study (Kanno T et al.: J. Pediatr. Gastr. Nutr. 24: 242-252, 1997). In the same period, serum potassium concentration in the newborn rats decreased significantly (p<0.01) from 7.2±0.1 (7d) to 6.7±0.1 mEq// (14d). All these results suggest that a renal potassium excretion system in the rat develops at least in the second week of life, and its capacity is high enough to excrete the daily potassium intake.

Original languageEnglish
Pages (from-to)745-752
Number of pages8
JournalJapanese Journal of Physiology
Volume51
Issue number6
DOIs
Publication statusPublished - Dec 1 2001
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physiology

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