Blood Research Institute of Wisconsin 1 article published in JoVE Biology Two-photon Imaging of Intracellular Ca2+ Handling and Nitric Oxide Production in Endothelial and Smooth Muscle Cells of an Isolated Rat Aorta Bradley T. Endres1,2, Alexander Staruschenko1, Marie Schulte4, Aron M. Geurts1,2,3, Oleg Palygin1 1Departments of Physiology, Medical College of Wisconsin, 2Human and Molecular Genetics Center, Medical College of Wisconsin, 3Cardiovascular Center, Medical College of Wisconsin, 4Blood Research Institute of Wisconsin Vascular cell functiondepends on activity of intracellular messengers. Described here is an ex vivo two photon imaging method that allows the measurement of intracellular calcium and nitric oxide levels in response to physiological and pharmacological stimuli in individual endothelial and smooth muscle cells of an isolated aorta.