Coronary artery vasospasm. The coronary vasculature was perfused with Microfil, a liquid latex medium, as described previously (20). Microvascular perfusion was visualized by transillumination under low-power magnification. (upper left panel) Normal microvasculature of a littermate control male mouse. (upper right panel and lower panels) Examples of focal artery stenoses in three Sur2^–/– mice. Arrows indicate significant coronary artery stenoses.