Effect of adrenalectomy on distal nephron lithium reabsorption induced by potassium depletion.
In potassium-depleted rats lithium is reabsorbed by an amiloride-sensitive transport mechanism in the distal nephron segments, and the urinary fractional excretion of lithium (FE[Li]) is reduced by almost 50% compared to that of potassium-replete rats. We have used renal clearance techniques to study the effects of adrenalectomy (Adx) or sham operation on amiloride-sensitive lithium reabsorption in conscious potassium-deprived (K5) and control (K200) rats. In the sham-operated rats, administration of a low potassium diet led to a significant reduction in FE(Li) from 27.0 to 16.6% (p < 0.01), whereas in the Adx rats the reduction in FE(Li) was smaller (from 27.0 to 22.6) and not statistically significant. Urinary sodium excretion was similar (1,100 nmol/min/100 g body weight) in all groups. During subsequent amiloride infusion in order to block the distal nephron reabsorption of lithium, urinary sodium excretion increased nearly twofold in the sham-operated groups whereas no change was evident in the Adx rats. Similarly, amiloride led to an increase in FE(Li) in the sham-K5 group but failed to increase FE(Li) in the Adx-K5 group. The results suggest that amiloride-sensitive lithium transport seen during potassium depletion is influenced by the presence of the adrenal glands, most likely due to their production of aldosterone.
Thomsen
K
K
Department of Biological Psychiatry, Institute for Basic Psychiatric Research, Psychiatric Hospital in Aarhus, Denmark.
Shalmi
M
M
D000311:Adrenal Glands / Q000502:physiology*; D000315:Adrenalectomy; D000450:Aldosterone / Q000096:biosynthesis; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004232:Diuretics / Q000494:pharmacology; D005260:Female; D007408:Intestinal Absorption / Q000502:physiology*; D008094:Lithium / Q000493:pharmacokinetics*; D008657:Metabolic Clearance Rate; D009399:Nephrons / Q000378:metabolism*; D017419:Potassium, Dietary / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar
D004232:Diuretics; D017419:Potassium, Dietary; D000450:Aldosterone; D000584:Amiloride; D008094:Lithium