Electrical characteristics of the mammalian distal tubule: Comparison of Ling-Gerard and macroelectrodes.
Studies were performed to 1) systematically compare Ling-Gerard microelectrodes and electrodes with large tips (3 to 5 mu O.D.) in the measurement of the transepithelial potential difference (PD) in the mammalian distal tubule and 2) to examine the sign and magnitude of the transepithelial PD along the length of the distal tubule. Recordings made with the tips of both types of electrodes placed together in the same tubule segment demonstrated no difference in transepithelial PD. Rapid influx of tubular fluid into the macroelectrode, however, was found to depolarize the tubular membrane, as recorded by both types of electrodes simultaneously. Technical critera were therefore established to prevent rapid influx of fluid and efflux of potassium chloride, filling the electrode, in the use of exploring electrodes with large tips. The sign of the transepithelial PD in early distal tubule was found to be negative and averaged -17.7 +/- 9.4 (mean +/- SEM) in Sprague-Dawley rats and approximately -12 mV in Wistar-Munich rats. The site of puncture was identified by dye transit time rate, microdissection, and cell morphology. The transepithelial PD increased along the length of the distal tubule and averaged -41.9 +/- 8.5 in the last portion accessible to examination.
D000818:Animals; D004560:Electricity; D004566:Electrodes; D005260:Female; D007684:Kidney Tubules / Q000502:physiology*; D007686:Kidney Tubules, Distal / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D008839:Microelectrodes; D009399:Nephrons / Q000502:physiology; D051381:Rats