Catecholamine release from fractionated chromaffin cells

Bovine chromaffin cells were separated by density gradient centrifugation into subfractions. After centrifugation on a self-generating Percoll gradient (42.75% isotonic Percoll, 30,000 x g for 22 min at 20 degrees C), the chromaffin cells were found in two clearly distinguishable peaks. The peak with the lower density contained most of the noradrenaline-producing cells (approximately 80%), whereas the adrenaline-producing cells were equally distributed between the two peaks. After collection of suitable fractions from the gradient, cell cultures were obtained, which were enriched with either > 90% adrenaline- or approximately 65% noradrenaline-producing cells. When stimulated by nicotine or carbachol, the dose-response curves of both cell fractions yielded similar EC50s for the release of adrenaline and noradrenaline. On the other hand, the cells of the less dense fraction released 30% more catecholamines (adrenaline as well as noradrenaline) than the cells of the more dense fraction. It is suggested that there are subpopulations among the adrenaline- and noradrenaline-producing cells with differences in receptor-effector coupling.