Abstract
1. In order to investigate the lithiuretic effect of frusemide, simultaneous measurements of fractional lithium excretion (FELi) and fractional fluid delivery to the end of the proximal convoluted tubules were made in Inactin-anaesthetized rats, first during a control period, then during intravenous infusion of frusemide at either 0.8 or 8.0 mg kg-1 h-1. Fluid balance was maintained by infusion of NaCl-KCl solution adjusted to match urinary excretion rates; measurements were made after urine flow had stabilized. 2. In time-control animals, which did not receive frusemide, no significant changes were observed in either FELi or fractional fluid delivery to the end of the proximal convoluted tubules (determined as the plasma/tubular fluid inulin concentration ratio, P/TFIn). 3. In animals given the high dose of frusemide, FELi increased from 0.22 +/- 0.02 (mean +/- S.E.M.) during the control period to 0.45 +/- 0.03 during frusemide infusion (P less than 0.001); this was accompanied by a modest increase in P/TFIn, from 0.43 +/- 0.02 to 0.51 +/- 0.02 (P less than 0.01). 4. In animals given the lower dose of frusemide, FELi increased from 0.21 +/- 0.01 to 0.37 +/- 0.01 (P less than 0.001). In this group, however, there was no discernible change in P/TFIn (0.43 +/- 0.02 vs. 0.44 +/- 0.01, not significant). 5. These results suggest that under control conditions a significant component of lithium reabsorption may occur beyond the proximal tubule, most likely in the loop of Henle.
Full text
PDF








Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Atherton J. C., Green R., Hughes S., McFall V., Sharples J. A., Solomon L. R., Wilson L. Lithium clearance in man: effects of dietary salt intake, acute changes in extracellular fluid volume, amiloride and frusemide. Clin Sci (Lond) 1987 Dec;73(6):645–651. doi: 10.1042/cs0730645. [DOI] [PubMed] [Google Scholar]
- Christensen S., Shalmi M., Petersen J. S. Lithium clearance as an indicator of proximal tubular sodium handling during furosemide diuresis. J Pharmacol Exp Ther. 1988 Aug;246(2):753–757. [PubMed] [Google Scholar]
- Christensen S., Steiness E., Christensen H. Tubular sites of furosemide natriuresis in volume-replaced and volume-depleted conscious rats. J Pharmacol Exp Ther. 1986 Oct;239(1):211–218. [PubMed] [Google Scholar]
- Dorhout Mees E. J., Beutler J. J., Boer W. H., Koomans H. A. Does lithium clearance reflect distal delivery in humans? Analysis with furosemide infusion. Am J Physiol. 1990 Apr;258(4 Pt 2):F1100–F1104. doi: 10.1152/ajprenal.1990.258.4.F1100. [DOI] [PubMed] [Google Scholar]
- Hayslett J. P., Kashgarian M. A micropuncture study of the renal handling of lithium. Pflugers Arch. 1979 Jun 12;380(2):159–163. doi: 10.1007/BF00582152. [DOI] [PubMed] [Google Scholar]
- Kirchner K. A. Lithium as a marker for proximal tubular delivery during low salt intake and diuretic infusion. Am J Physiol. 1987 Jul;253(1 Pt 2):F188–F196. doi: 10.1152/ajprenal.1987.253.1.F188. [DOI] [PubMed] [Google Scholar]
- Koomans H. A., Boer W. H., Dorhout Mees E. J. Evaluation of lithium clearance as a marker of proximal tubule sodium handling. Kidney Int. 1989 Jul;36(1):2–12. doi: 10.1038/ki.1989.153. [DOI] [PubMed] [Google Scholar]
- Leyssac P. P., Holstein-Rathlou N. H., Skøtt P., Alfrey A. C. A micropuncture study of proximal tubular transport of lithium during osmotic diuresis. Am J Physiol. 1990 Apr;258(4 Pt 2):F1090–F1095. doi: 10.1152/ajprenal.1990.258.4.F1090. [DOI] [PubMed] [Google Scholar]
- Maack T. Renal clearance and isolated kidney perfusion techniques. Kidney Int. 1986 Aug;30(2):142–151. doi: 10.1038/ki.1986.166. [DOI] [PubMed] [Google Scholar]
- Schlatter E., Salomonsson M., Persson A. E., Greger R. Macula densa cells sense luminal NaCl concentration via furosemide sensitive Na+2Cl-K+ cotransport. Pflugers Arch. 1989 Jul;414(3):286–290. doi: 10.1007/BF00584628. [DOI] [PubMed] [Google Scholar]
- Shirley D. G., Walter S. J., Thomsen K. A comparison of micropuncture and lithium clearance methods in the assessment of renal tubular function in rats with diabetes insipidus. Pflugers Arch. 1983 Dec;399(4):266–270. doi: 10.1007/BF00652750. [DOI] [PubMed] [Google Scholar]
- Shirley D. G., Zewde T., Walter S. J. Renal function in normal and potassium-depleted rats before and after preparation for micropuncture experimentation. Pflugers Arch. 1990 Apr;416(1-2):74–79. doi: 10.1007/BF00370225. [DOI] [PubMed] [Google Scholar]
- Steele T. H., Dudgeon K. L., Larmore C. K. Pharmacological characterization of lithium reabsorption in the rat. J Pharmacol Exp Ther. 1976 Jan;196(1):188–193. [PubMed] [Google Scholar]
- Thomsen K., Holstein-Rathlou N. H., Leyssac P. P. Comparison of three measures of proximal tubular reabsorption: lithium clearance, occlusion time, and micropuncture. Am J Physiol. 1981 Oct;241(4):F348–F355. doi: 10.1152/ajprenal.1981.241.4.F348. [DOI] [PubMed] [Google Scholar]
- Thomsen K., Leyssac P. P. Acute effects of various diuretics on lithium clearance. Studies in rats on medium and low sodium diet. Ren Physiol. 1986;9(1-2):1–8. [PubMed] [Google Scholar]
- Thomsen K. Lithium clearance: a new method for determining proximal and distal tubular reabsorption of sodium and water. Nephron. 1984;37(4):217–223. doi: 10.1159/000183252. [DOI] [PubMed] [Google Scholar]
- Thomsen K., Schou M. Renal lithium excretion in man. Am J Physiol. 1968 Oct;215(4):823–827. doi: 10.1152/ajplegacy.1968.215.4.823. [DOI] [PubMed] [Google Scholar]
- Walter S. J., Laycock J. F., Shirley D. G. A micropuncture study of proximal tubular function after acute hydrochlorothiazide administration to Brattleboro rats with diabetes insipidus. Clin Sci (Lond) 1979 Nov;57(5):427–434. doi: 10.1042/cs0570427. [DOI] [PubMed] [Google Scholar]
