17β‐estradiol induces Ca 2+ signaling in distal convoluted tubules and connecting tubules through G‐protein coupled estrogen receptor 1

Steroid hormones are known to modulate ion transport in the kidney at the genomic level and, in addition, to cause rapid non‐genomic responses in a variety of other tissues. Little is known about renal short‐term effects of single steroid hormones, and we therefore studied the immediate actions of steroids on intracellular Ca 2+ signaling on isolated distal convoluted tubules (DCT2s) and connecting tubules (CNTs). By Fluo‐4 fluorometry, we demonstrated that physiological concentrations of 17β‐estradiol (E2) rapidly induced transient increases in the intracellular Ca 2+ concentration in a subpopulation of cells in DCT2/CNT. DCT2 and CNT segments were identified by endogenous fluorescence of TRPV5‐promoter driven EGFP. The Ca 2+ increase was dependent on extracellular Ca 2+ and was inhibited by Gd 3+ . The E2 antagonists ICI 182,780 enhanced the Ca 2+ signals, which is inconsistent with activation through classical E2 receptors. The involvement of the G‐protein coupled estrogen receptor1 (GPER1) was suggested by mimicking the effect of E2 with the GPER1 agonist, G‐1. GPER1 mRNA was detected in micro‐dissected DCT2/CNT by RT‐PCR and GPER1 protein was immunolocalized to intercalated cells in CNT and CCD. As E2 failed to induce Ca 2+ signaling in GPER1 knockout mice, we propose that this receptor is necessary for E2 to evoke rapid intracellular Ca 2+ signaling in DCT2/CNT. Supported by the Lundbeck Foundation.