A common animal model for various human maladies, the rat has been widely employed in the study of coronary heart disease, the single leading cause of death in the United States today. Coronary heart disease is characterized by an insufficient supply of blood to the myocardium, usually due to the build up of plaques in the arteries. Pain may arise in the chest, a condition known as angina, due to the lack of enough oxygen, which is carried by the blood, to the heart. If the blood supply to the myocardium becomes completely blocked, a heart attack ensues. A variety of treatments for coronary heart disease are commonly used, and many researchers are attempting to develop better ones. Studies, such as one completed in 2004 in which gene therapy was successfully utilized to restore the failing hearts of rats to normal activity levels, provide great hope that more effective treatments for heart disease are on the horizon.

In order to localize a red fluorescent tag to F-actin in the sample of rat heart tissue presented in the digital image above, the specimen was labeled with Alexa Fluor 568 conjugated to a phallotoxin (phalloidin). Oregon Green 488 conjugated to the lectin wheat germ agglutinin, which selectively binds to N-acetylglucosamine and N-acetylneuraminic residues, was also applied to the tissue sample, as was the nuclear counterstain Hoechst 33342. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.