[The use of thin slices of myocardium for recording the currents across single ion channels].

Thin cardiac slices (100-200 microns) from newborn (1-14 days old) rat heart ventricles were used for patch clamp recordings. High resistance seals (10-50 GOhms) between patch-clamp pipettes and the membrane of cardiac cells as well as classical patch-clamp configurations can be achieved on this preparation without any enzymatic treatment of tissue. Resisting potential for cardiac cells measured in whole-cell configuration ranged between -30 and -65 mV. Averaged sodium currents and single inward rectifying potassium elementary currents recorded in cell-attached mode displayed basic features similar to those previously reported for isolated rat ventricular cells. Application of the method described here in cardiac electrophysiology will allow patch-clamp studies on heart cells without the complicated procedures of cell isolation. In addition, the uncertainty associated with enzyme treatment can be avoided. In future, this technique could be a new tool for studying electrophysiological properties of heart cells in situ.