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Oscillatory juxtaglomerular tubular cells – a possible new tubule‐to‐arteriole signaling pathway
Author(s) -
Komlosi Peter,
Fintha Attila,
Bell Phillip Darwin
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb39
Subject(s) - macula densa , afferent arterioles , efferent , arteriole , tubuloglomerular feedback , distal convoluted tubule , chemistry , anatomy , microbiology and biotechnology , biology , nephron , endocrinology , angiotensin ii , kidney , afferent , renin–angiotensin system , blood pressure , circulatory system
Tubular segments distal (downstream) and proximal (upstream) to the macula densa are closely associated with the afferent and efferent arterioles, respectively. The epithelial cells in the perimeter of the macula densa demonstrate spontaneous oscillations in intracellular calcium concentration ([Ca 2+ ] i ). We hypothesized that intracellular Ca 2+ signaling in the tubular segment proximal to the macula densa might be associated with intracellular Ca 2+ changes in the adjacent efferent arteriole. We utilized isolated perfused cortical thick ascending limb (cTAL) with attached glomerulus‐efferent arteriole and assessed [Ca 2+ ] i in the tubular and vascular elements with widefield fluorescence microscopy using fura‐2 or multiphoton excitation fluorescence microscopy and 4‐dimensional volume‐rendering. Here we report that the vascular smooth muscle cells of the efferent arteriole and the epithelial cells of the adjacent cTAL demonstrate synchronous oscillations or spikes in [Ca 2+ ] i . Interestingly, the initiation of an oscillation in [Ca 2+ ] i in the efferent arteriole required [Ca 2+ ] i in the tubular epithelium to reach an apparent threshold. Dissection of the efferent arteriole away from the cTAL reduced the amplitude of oscillations in the efferent arteriole. Also, luminal administration of furosemide, an inhibitor of the Na + :2Cl − :K + cotransporter, blocked the amplitude of oscillations in the epithelial cells of the cTAL by 53 %, hydrochlorothiazide from the lumen had no effect. These findings suggest that the tubular segment downstream from the macula densa possess oscillations in [Ca 2+ ] i which may play a role in signaling to the efferent arteriole.