What are chromaffin cells?

Ever wonder where that surge of energy comes from when you hear the starting gun at the beginning of a race?

In large measure, it comes from the release of adrenaline into the blood stream. The cells that release the adrenaline in response to the gun blast are deep within your adrenal glands (you have two of them located just above your kidneys). These adrenaline-containing cells are called "chromaffin cells" because someone found that they show up under the microscope when stained with chromium salts. Much more is now known about "chromaffin cells." For example, it is known that when these cells are stimulated to release adrenaline, they also release enkephalins, small opiate-like peptides, that some people say are responsible for the euphoria that runners sometimes feel when they go jogging, some so much that they bcome addicted to jogging.

But let us get back to the adrenaline that is released from the chromaffin cells into your blood stream. Where does it go ? What does it do? Well, for a start, adrenaline is a hormone and stimulates cells in other organs and tissues far away from the adrenal gland. It influences the muscle of your heart, increasing the force of contraction so blood can be pumped to peripheral tissues (such as leg muscles) more quickly and effectively, so you can start your race as quickly as possible. Another site of action is the liver, where it increases the rate of release of sugar from your liver into the blood stream, as well as increasing the destruction of toxic materials. Release of adrenaline from chromaffin cells in the adrenal medulla can be increased up to 5-fold in response to fear, pain, and physical exercise.

Much of what we know about chromaffin cell function comes from studies in several laboratories over the last 10 years, using chromaffin cells in cell culture. Large numbers of chromaffin cells (more than a million) are present in the adrenal glands of cattle which provide a ready source of experimental material at minimal cost. Chromaffin cells are obtained by simply perfusing the adrenal gland through its central blood vessel with a solution of collagenase, which breaks down the material that holds the chromaffin cells together in the intact adrenal medulla.