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Nigerian Journal of Physiological Sciences
Physiological Society of Nigeria
ISSN: 0794-859X
Vol. 32, No. 1, 2017, pp. 1-6
Bioline Code: np17001
Full paper language: English
Document type: Research Article
Document available free of charge

Nigerian Journal of Physiological Sciences, Vol. 32, No. 1, 2017, pp. 1-6

 en Circadian Potassium Excretion is Unaffected Following Furosemide Induced Increase in Sodium Delivery to the Distal Nephron
Ilenwabor, B.P.; Asowata, E.O. & Obika, L.F.

Abstract

Summary: The mineralocorticoid aldosterone is widely accepted as a key regulator of K+ balance as well as urinary K+ excretion. However, recent evidence suggests that the circadian control of K+ excretion is independent of aldosterone. The delivery of Na+ to the distal nephron is known to be an important determinant of aldosterone mediated secretion of K+ in this segment of the nephron. Examining the link between distal Na+ delivery and K+ excretion; and how this link affect circadian K+ excretion will advance what is currently known about the maintenance of K+ homeostasis. In the current study, we investigated the effect of furosemide-induced increase in distal tubular Na+ on K+ excretion. Na+, K+ and aldosterone levels were measured in 12-hour day time and 12-hour night time urine samples following furosemide administration, and compared with controls in 10 apparently healthy male subjects. To confirm the increased delivery of Na+ to the distal nephron by furosemide, increased Na+ excretion and aldosterone activity was observed in subjects administered furosemide. Consistent with previous reports, night time K+ excretion was significantly lower than day time, and this observation was unchanged even with increased Na+ delivery to the distal tubules. In healthy individuals, aldosterone increases K+ secretion and this is known to further increase with increased Na+ delivery to the potassium secreting segment of the nephron. Even though the administration of furosemide increased aldosterone activity and the delivery of Na+ to the distal tubules, the dip in night time K+ excretion was unchanged. Our findings suggest that the circadian control of K+ excretion is not linked to Na+ levels and thus independent of aldosterone.

Keywords
Na+/K+ ratio; circadian rhythm; aldosterone; furosemide; distal nephron; kidney

 
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