Cortisol mediated synchronization of circadian rhythm in urinary potassium excretion

M. C. Moore-Ede, W. S. Schmelzer, D. A. Kass, J. A. Herd

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31 Scopus citations


Conscious chair-acclimatized squirrel monkeys (Saimiri sciureus) studied with lights on (600 lx) from 0800 to 2000 h daily (LD 12:12) display a prominent circadian rhythm in renal potassium excretion. The characteristics of this rhythm were reproduced in adrenalectomized monkeys by infusing 5 mg cortisol and 0.001 mg aldosterone, or 5 mg cortisol alone, between 0800 and 0900 h daily. When the timing of cortisol administration (with or without aldosterone) was phase-delayed by 8 h, the urinary potassium rhythm resynchronized by 80% of the cortisol phase shift, but only after a transient response lasting 3-4 days. With the same daily dose of adrenal steroids given as a continuous infusion throughout each 24 h, urinary potassium excretion showed free-running oscillations no longer synchronized to the light-dark cycle. These results indicate that the circadian rhythm of plasma cortisol concentration acts as an internal mediator in the circadian timing system, synchronizing a potentially autonomous oscillation in renal potassium excretion to environmental time cues and to other circadian rhythms within the animal.

Original languageEnglish (US)
Pages (from-to)R230-R238
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number3
StatePublished - 1977
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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