Surface plasmon assisted microscopy: Reverse kretschmann fluorescence analysis of kinetics of hypertrophic cardiomyopathy heart

It is believed that the alteration of the kinetics of interaction between actin and myosin causes a serious heart disease called Familial Hypertrophic Cardiomyopathy (FHC) by making a heart pump blood inefficiently. To check this hypothesis in ex-vivo heart, we constructed Surface Plasmon Assisted Microscope (SPAM) and used it in a reverse Kretschmann (RK) configuration. In SPAM fluorescence is the result of nearfield coupling of fluorophores excited in the vicinity of the metal coated surface of a coverslip with the surface plasmons propagating in the metal. Surface plasmons decouple on opposite side of the metal film and emit in directional manner as a far-field ppolarized radiation. In RK-SPAM a sample is illuminated directly by the laser beam. During contraction of heart muscle a myosin cross-bridge imparts periodic force impulses to actin. The impulses were analyzed by RK-SPAM by Fluorescence Correlation Spectroscopy (FCS) of fluorescently labeled actin. The rate of changes of orientation were significantly faster in contracting cardiac myofibrils of transgenic (R58Q) mice than of wild type (WT). These results suggest a way to rapidly diagnose this disease.