Applying Atomic Force Microscopy to Studies in Cardiac Physiology

At the present time there exists a great deal of interest in the application of scanning probe microscopy methods to the imaging of cellular systems (1 ,2 ). It would now not be an exaggeration to state that atomic force microscopy (AFM), in particular, represents perhaps the most powerful means of structural/functional analysis at the level of a single live cell. In recent years this technology has been applied, amongst many other systems, to studies of bacterial flagella (3 ), erythrocytes (4 ), human platelets (5 ), endothelial cells (6 ), skin fibroblasts (7 ), plant cuticles (8 ), and cardiac myocytes (9 ). In resolution terms, perhaps the most impressive work is that of Engel et al. (10 ). Although not on whole cells (thereby greatly simplifying the experiment), molecular-level images of isolated cellular gap junctions, which play an important role in intracellular communication and signal transduction, have been obtained. More recently, experimental protocols have advanced to the point where it is possible to monitor, simultaneously, both cellular topography and ion channel flux (11 ). The ability to characterize functionally active cellular systems at a nanometre resolution under controlled fluid conditions has also been used in the monitoring of time-dependent cellular change (12 ,13 ).