The conditions for the nuclei isolation from cardiomyocytes for electrophysiological studies of ion channels in the native nuclear membrane were optimized. The structural and functional intactness of isolated nuclei is crucial for investigation of the biophysical properties of the transport systems in the native nuclear membrane. The quality of the obtained sample was evaluated by ion currents recording through the nuclear membrane in nucleus-attached or excised patch configuration at voltage-clamp mode of patch-clamp technique. In our study the solutions with different compositions were tested and the quality of the samples obtained using different methods of myocardium homogenization were compared. We found that the activity of ion channels in the nuclear membrane were most often registered when myocardium was homogenized in solution with the next composition (mmol/l): sucrose – 300, KCl – 60, HEPES – 10 (pH 7,2) with protease inhibitors cocktail, DL-dithiothreitol (1 mmol/l) and glycerol, using glass homogenizer (Dounce).