STEM-CELL FACTOR ALTERS MEMBRANE-POTENTIAL OF PURIFIED PERITONEAL MAST-CELLS IN CULTURE

The membrane potential (E(m)) was used as an indicator to evaluate the effect of stem cell factor (SCF) on the membrane integrity of periton eal mast cells (PMCs). PMCs were harvested from the peritoneal lavage of Sprague-Dawley rats, purified more than 95% and cultured with or wi thout the presence of SCF (2 x 10(-8) M). E(m) values were measured wi th conventional intracellular recording techniques. Results from day 1 to day 4 in culture were compared. Significant differences in average E(m) (aE(m)) (P < 0.01, analysis of variance) were seen on days 3 and 4 (means +/- SE in millivolts): -67.4 +/- 8.0 and -59.4 +/- 4.8 with SCF vs. -24.8 +/- 7.9 and -7.6 +/- 3.9 without SCF, respectively. More over, after culture with SCF for >1 wk, the aE(m) values of purified P MCs had a tendency to reach plateau values similar to that of unpurifi ed PMCs on day 1 (at -20 mV). The morphological appearances of PMCs ca n be correlated with the results of aE(m) measurements. PMCs with a sm ooth spherical shape and highly refractive appearance, and better tole rance to electrode impalement, showed E(m) with greater negative value s and lesser fluctuations. These results indicate that SCF can maintai n the membrane properties and viability of purified PMCs in a long-ter m culture.