Propagated Endothelial Ca 2+ Waves and Arteriolar Dilation In Vivo

• DOI: 10.1161/circresaha.107.149484
• Publication Date: 2007-10-12T01:17:22Z
• Authors: Yvonne N. Tallini; Johan Fredrik Brekke; Bo Shui; Robert Doran; Seong-min Hwang; Junichi Nakai; Guy Salama; Steven S. Segal; Michael I. Kotlikoff
• Keywords: Cremaster muscle; Arteriole

To study endothelial cell (EC)- specific Ca(2+) signaling in vivo we engineered transgenic mice which the sensor GCaMP2 is placed under control of endogenous connexin40 (Cx40) transcription regulatory elements within a bacterial artificial chromosome (BAC), resulting high expression arterial ECs, atrial myocytes, and cardiac Purkinje fibers. High signal/noise signals were obtained Cx40(BAC)-GCaMP2 ventricular network vitro ECs cremaster muscle arterioles vivo. Microiontophoresis acetylcholine (ACh) onto triggered transient increase EC fluorescence that propagated along arteriole with an initial velocity approximately 116 microm/s (n=28) decayed over distances up to 974 microm. The local rise was followed (delay, 830+/-60 ms; n=8) by vasodilation conducted rapidly (mm/s), bidirectionally, into branches for exceeding 1 mm. At intermediate (300 600 microm), rapidly-conducted occurred without changing Ca(2+), additional dilation after arrival wave. In contrast, focal delivery sodium nitroprusside evoked similar dilations or conduction. We conclude responses ACh consists 2 phases: (1) initiated but independent at remote sites; (2) slower complementary associated wave propagates endothelium.