Oscillating cortical thick ascending limb cells at the juxtaglomerular apparatus.
While studying the intracellular calcium dynamics in cells of the macula densa, the observation was made that tubular epithelial cells located near the macula densa and associated with the renal arterioles exhibit spontaneous Ca2+ oscillations. In this study, the cortical thick ascending limb-distal tubule, with attached glomerulus, was isolated and perfused. At a low luminal sodium chloride concentration, Ca2+ oscillations at a frequency of 63 mHz were observed in tubular cells that were within 100 microm of the macula densa plaque using four-dimensional multiphoton microscopy and wide-field fluorescence microscopy with fura-2. The Ca2+ oscillations were absent in the macula densa cells. Spontaneous oscillations in basolateral membrane potential suggested that Ca2+ oscillations occurred, at least in part, through depolarization-induced increases in Ca2+ entry. The amplitude of these Ca2+ oscillations was significantly enhanced by the activation of the Ca2+-sensing receptor. Increasing the luminal sodium chloride concentration or luminal flow resulted in a significant increase in both the amplitude of Ca2+ oscillations and the intracellular Ca2+ concentration in perimacular cortical thick ascending limb cells. In addition, luminal furosemide attenuated the [NaCl]L-dependent changes in intracellular Ca2+ concentration, but hydrochlorothiazide had no effect. These findings demonstrate that tubular epithelial cells at the perimeter of the macula densa exhibit spontaneous oscillations in intracellular Ca2+ concentration, enhanced by tubular flow and luminal sodium chloride. These oscillatory patterns may play a role in juxtaglomerular signaling.
Komlosi
Peter
P
Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina, USA. komlosi@musc.edu
Banizs
Boglarka
B
Fintha
Attila
A
Steele
Stacy
S
Zhang
Zhi-Ren
ZR
Bell
P Darwin
PD
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D018929:Cell Culture Techniques; D004847:Epithelial Cells / Q000502:physiology*; D007606:Juxtaglomerular Apparatus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D007686:Kidney Tubules, Distal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008138:Loop of Henle / Q000378:metabolism* / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D049990:Membrane Transport Modulators / Q000494:pharmacology; D036641:Microscopy, Fluorescence, Multiphoton; D011817:Rabbits
D049990:Membrane Transport Modulators