Acute effects of angiotensin II on calcium influx in the podocytes of the freshly isolated glomeruli of the wild type and TRPC6‐deficient mice (892.1)

Podocytes play a key role in regulating glomerular permeability and maintaining glomerular structure. It was previously reported that angiotensin (Ang II) enhances albuminuria and increases calcium flux in podocytes by activating TRPC6 channels. The goal of this study was to examine acute effects of Ang II on intracellular calcium levels and endogenous ion channels activity in their native setting, podocytes of freshly isolated mouse glomeruli. Single channel patch‐clamp experiments demonstrated that an ion channel with distinct TRPC6 properties (22 pS) was present in the wild type animals, however it was not identified in TRPC6 knockout mice. Ang II acutely activated these native channels in the podocytes of wild type, but not TRPC6 deficient mice; the effect was mediated by changes in the channel open probability. Data obtained in CHO cells transiently expressed with TRPC6 and AT1R confirmed these findings. We further measured alterations in intracellular calcium stimulated by Ang II in the presence and absence of the TRPC inhibitors gadolinium chloride and SKF 96365, and TRPC6 activator flufenamic acid; these experiments were performed in Fluo4/FuraRed loaded podocytes of the intact glomeruli of the wild type and TRPC6‐deficient mice. Our data have provided the first direct evidence of Ang II‐dependent activation of TRPC6 channels and calcium influx in podocytes, which might play a significant role in the pathogenesis of glomerular diseases. Grant Funding Source : Supported by NIH HL108880, DK079968, Z01‐ES‐101684, ADA 1‐10‐BS‐168, ASN Ben J Lipps Fellowship