METHOD FOR ISOLATION OF HUMAN VENTRICULAR MYOCYTES FROM SINGLE ENDOCARDIAL AND EPICARDIAL BIOPSIES

The study of adult human ventricular cells has been limited by tissue availability. In this study we describe techniques for the isolation o f Ca2+-tolerant adult human ventricular cells from both transvenous en domyocardial and epicardial biopsies. Ca2+-tolerant cells were obtaine d from 80% of the biopsies processed. Although the yield of Ca2+-toler ant myocytes from either type of biopsy was low (1-5%), myocytes with normal resting potentials and action potentials can be obtained from s ingle biopsy specimens, providing a source of normal human myocytes fo r electrophysiological study. Resting potentials (V-rest) were recorde d in 41 isolated right ventricular endomyocardial cells at 37 degrees C. Sixteen cells were depolarized (V-rest = -26 +/- 13 mV), and 25 cel ls had normal resting potentials (V-rest = -84 +/- 6 mV). Action poten tials were recorded in 16 cells. At a pacing cycle length of 1 s, 4 ce lls had prolonged action potential duration at 90% (APD(90), 718 +/- 2 6 ms) and 10 cells had normal APD(90) (381 +/- 94 ms) compared with th ose recorded from intact right ventricular septal trabeculae from expl anted hearts. Voltage-clamp studies of isolated human ventricular myoc ytes obtained from these biopsies document the presence of currents pr eviously reported from cells isolated from explanted hearts.