Immobilized heart cells

Early attempts to functionalize biomaterial surfaces with biological molecules were focused on improving blood compatibility of cardiovascular devices, such as the artificial heart and synthetic blood vessels, by immobilizing heparin or albumin on polyurethane or Dacron . To enhance cell adhesion to biomaterial surfaces, entire extracellular matrix (ECM) proteins, such as fibronectin and laminin, have been used directly as coatings. However, because of the nonspecific manner of whole protein adsorption, most of the cell binding capability is often lost. Using a molecular templating technique, it may be possible to select which protein(s) to absorb on biomaterial surfaces. ... 

It has been shown that a concentration of 1 mmol/1 cesium in Tyrode solution as the outer medium of cardiac Purkinje fibers — part of the excitable system of the heart — is sufficient to suppress the potassium outward current (pacemaker current) nearly completely . When the concentration of cesium exceeds 20 mmol/1 all detectable potassium currents in cardiac Purkinje fibers are blocked. Since this effect occurred within one or two minutes it was believed that cesium ions are able to block the potassium channels in the membrane from the outside. One possible explanation would be based upon the fact that cesium ions are bigger than potassium ions (diameter [Cs] = 1.77 A [K]" = 1.33 A). Therefore, if they eventually invade the potassium channels, they should be hampered in their motion or even immobilized because of their bigger size. If this was the case, cesium ions would invade potassium channels whenever they reach cell membranes and would irreversibly block them. Besides, cesium ions should not be detectable inside the cells of the excitable system, since they are imable to penetrate the cell membranes. 

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