What is responsible for the diurnal variation in potassium excretion?
Am J Physiol
; 267(2 Pt 2): R554-60, 1994 Aug.
Article
em En
| MEDLINE
| ID: mdl-8067468
ABSTRACT
Potassium excretion exhibits a diurnal pattern, with most excretion occurring close to noon in humans. Each component of the K+ excretion rate [urinary K+ concentration ([K+]) and flow rate] was measured and back-calculated to reflect events in the cortical collecting duct (CCD). Our purpose was to determine to what extent each component contributed to this diurnal variation in each 2-h portion of the day. In humans, K+ excretion rose threefold from nadir (0600 h) to peak (1200-1400 h), 18 h after the principal intake of K+. The variation in K+ excretion was due almost exclusively to changes in [K+] in the terminal CCD ([K+]CCD) rather than via changes in flow rate. In rats, the bulk of K+ excretion occurred shortly after eating. Both components of K+ excretion rose after meals; the rise in the [K+]CCD (3.3-fold) predominated at earlier times, and the rise in flow rate occurred later and was primarily a result of a higher rate of excretion of urea. The rise in [K+]CCD did not correlate with aldosterone levels or administration. A very large rise in the [K+]CCD only occurred in the presence of bicarbonaturia; the transtubular potassium concentration gradient was now close to 15 in the morning and evening.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Potássio
/
Ritmo Circadiano
Limite:
Adult
/
Animals
/
Female
/
Humans
/
Male
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1994
Tipo de documento:
Article
País de afiliação:
Canadá