A method for in situ measurement of ionic concentration in picoliter samples of renal tubular fluid

• Published in: Pflügers Archiv Vol. 401; no. 4; pp. 430 - 432
• Main Authors: HANSELL, P, SADOWSKI, J, SJOQUIST, M, ULFENDAHL, H. R
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-08-1984
• Subjects: Animals; Biological and medical sciences; Body Fluids - analysis; Fundamental and applied biological sciences. Psychology; Furosemide - analysis; Kidney Tubules - analysis; Kidney Tubules, Distal - analysis; Loop of Henle - analysis; Male; Methods; Osmolar Concentration; Physiology - instrumentation; Rats; Rats, Inbred Strains; Vertebrates: urinary system; Micropuncture; Rat; Rodentia; Electrophysiology; Concentration; Inorganic element; Kidney; Ion microanalysis; In vivo; Vertebrata; Renal tubule; Mammalia; Urinary system; Microelectrode; Electrical impedance
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/BF00584350

A method permitting rapid and frequent determination of the total ionic concentration in renal tubular fluid samples, by measuring sample electrical impedance, is described. No special electrodes or sophisticated equipment are required. Since picoliter volumes are sufficient for measurement, tubular fluid dynamics are not significantly disturbed by the sampling procedure. The sample is aspirated into the tip of the standard glass micropipette and its ionic concentration, in the range of 100-1000 mmol/l, can be determined by any sensitive impedance-measuring device. In the present studies the Wheatstone bridge of the Wiederhielm apparatus for pressure measurement in micropuncture studies was used for the purpose. The obvious limitation of the method is that the measurements do not include non-electrolytes and cannot differentiate between individual ion species.