Origin of electrical PD's in hamster thin ascending limbs of Henle's loop.
Microelectrodes with 2-micronm-tip diameters arranged to record differentially between this ascending limbs (ALH) and ascending vasa recta (AVR), gave values of 1.95 +/- 0.17 mV, ALH positive, in hydropenia with mineral oil bathing the kidney. Average values remained in the range of 1-2 mV when the ALH and AVR values were obtained sequentially, when the kidney was bathed in Ringer solution, when 5-8 Momega Ling-Gerard microelectrodes were used in the ALH, or when the hamsters were in saline diuresis. These results contradict reports of earlier studies with high impedance Ling-Gerard electrodes that the PD was -9 mV, ALH negative. Perfusion of ALH in saline diuresis with solutions of various compositions provided estimates of ionic transport numbers: tNa+ = 0.33 +/- 0.01, tK+ = 0.00 +/- 0.02, tC1- = 0.67 +/- 0.02. When the perfusion solution was designed to have the same Na+, K+, and C1- concentrations as AVR plasma, the PD was 1.36 +/- .20 mV; when ouabain or furosemide were included (10(-5) M), the PD declined 1.35 +/- 0.21 mV and 1.41 +/- 0.28 mV, respectively. The results suggest that active C1- transport is mainly responsible for the PD, but that diffusion potentials can contribute.
D000818:Animals; D002712:Chlorides / Q000494:pharmacology / Q000652:urine; D002794:Choline / Q000652:urine; D006224:Cricetinae; D003494:Cyclamates / Q000652:urine; D004058:Diffusion; D005665:Furosemide / Q000494:pharmacology; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007444:Inulin / Q000652:urine; D007684:Kidney Tubules / Q000502:physiology*; D008138:Loop of Henle / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008647:Mesocricetus; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology / Q000652:urine; D012964:Sodium / Q000494:pharmacology / Q000652:urine
D002712:Chlorides; D003494:Cyclamates; D010042:Ouabain; D005665:Furosemide; D007444:Inulin; D012964:Sodium; D002794:Choline; D011188:Potassium