Changes in endothelial [Ca2+]i in response to acetylcholine stimulation in an isolated pressurized artery (credit: Z Bagi)

Photomicrograph shows a precapillary coronary arteriole in the human heart.

Red: endothelial nitric oxide synthase; white: GTP cyclo-hydrolase; green: smooth muscle actin; blue: DAPI, nuclei (credit: M Balogh & A Szabo)

Photomicrogrpah shows a small coronary artery (longitudinal section) in the rat heart.

Red: caveolin-1; greeen: smooth muscle actin, blue: DAPI, nuclei (credit: A Feher & Z Bagi)