Use of chlortetracycline to monitor calcium mobilization during histamine secretion from the mast cell: a cautionary note.

Purified rat peritoneal mast cells incubated with chlortetracycline showed a fluorescence emission spectrum characteristic of the membrane-bound complex with calcium ions. Treatment of the cells with chelating agents, which are thought to deplete the mast cell of sequestered calcium, led to a marked reduction in fluorescence. Activation of the cells with a number of secretagogues produced an abrupt fall in fluorescence emission, indicative of the release of bound calcium, and an accompanying liberation of histamine. These changes were, however, blocked by metabolic inhibitors and anti-anaphylactic agents, suggesting that they occurred subsequently to the exocytotic process. The significance of these findings in the application of the method to other systems is discussed.