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ATP‐mediated intercellular calcium wave in renal (juxta)glomerular endothelial cells (GENC)
Author(s) -
Bansal Eric,
Toma Ildiko,
Kang Jung Julie,
PetiPeterdi Janos
Publication year - 2007
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.21.5.a499-c
Subject(s) - calcium , chemistry , biophysics , extracellular , t type calcium channel , calcium in biology , afferent arterioles , voltage dependent calcium channel , microbiology and biotechnology , medicine , endocrinology , biochemistry , biology , angiotensin ii , receptor , organic chemistry
Autoregulatory mechanisms of the afferent arteriole (AA), the myogenic response and tubuloglomerular feedback (TGF), both involve extracellular ATP and purinergic calcium signaling. The calcium wave of TGF propagates to both contractile and endothelial cells. We aimed to identify the role of the endothelial cell membrane potential (Vm) or calcium [Ca 2+ ] i in signal propagation. The in vitro microperfused juxtaglomerular apparatus (JGA) and GENC cultures were loaded with ANNINE‐6, a newly synthesized membrane‐specific voltage‐sensitive dye, and Fluo‐4/Fura red to visualize Vm and [Ca 2+ ] i in real‐time using fluorescence confocal microscopy. In contrast to smooth muscle cells, vasoconstriction produced significant [Ca 2+ ] i but no Vm signals in GENCs. Mechanical stimulation of a single GENC caused a 4 ± 0.7‐fold (n=18) increase in [Ca 2+ ] i which was propagated throughout the monolayer (8 ± 0.3 μm/s) in a regenerative manner (without decrement of amplitude, kinetics, and speed) over distances >200μm. Consistent with Vm measurements, the voltage‐dependent calcium channel blocker nifedipine (10 μM) had no effect. Initiation and propagation of the calcium wave most likely involves mechanosensitive cation channels in the stimulated cell and extracellular ATP, respectively, since addition of a calcium channel blocker (La 3+ ) or an ATP scavenger cocktail (apyrase and hexokinase, 50 U/ml each) abolished them. These results demonstrate the existence of an endothelial calcium wave in the renal vasculature which may serve an important feedback role during vasoconstriction.