CATECHOLAMINE RELEASE FROM FRACTIONATED CHROMAFFIN CELLS

Bovine chromaffin cells were separated by density gradient centrifugat ion into subfractions. After centrifugation on a self-generating Perco ll gradient (42.75% isotonic Percoll, 30 000 X g for 22 min at 20 degr ees C), the chromaffin cells were found in two clearly distinguishable peaks. The peak with the lower density contained most of the noradren aline-producing cells (similar to 80%), whereas the adrenaline-produci ng cells were equally distributed between the two peaks. After collect ion of suitable fractions from the gradient, cell cultures were obtain ed, which were enriched with tither > 90% adrenaline- or similar to 65 % noradrenaline-producing cells. When stimulated by nicotine or carbac hol, the dose-response curves of both cell fractions yielded similar E C(50)s for the release of adrenaline and noradrenaline. On the other h and, the cells of the less dense fraction released 30% more catecholam ines (adrenaline as well as noradrenaline) than the cells of the more dense fraction. It is suggested that there are subpopulations among th e adrenaline- and noradrenaline-producing cells with differences in re ceptor-effector coupling.