Activation of rat peritoneal mast cells in coculture with sympathetic neurons alters neuronal physiology.

Rat peritoneal mast cells (PMC) were activated with anti-IgE or 48/80 while in coculture with neurons dissociated from mouse superior cervical ganglia. At 18-24 h of coculture, microelectrode recordings from neurons were made 15 min after activation of PMC with anti-IgE antibody or the secretagogue compound 48/80. These recordings showed that PMC activation caused depolarization of the neurons and decreased their membrane resistance. Both methods of activation resulted in similar changes in these neuronal characteristics. The resting potential decreased by an average of 15% from the control value of -36.0 +/- 0.6 mV (SEM) (n = 121). The membrane resistance decreased by an average of 60% from the control value of 34.2 +/- 2.0 M omega (n = 75). Application of PMC secretion products directly onto neuronal somata caused reversible changes similar to those caused by activation of cocultured PMC. A decrease in membrane resistance that was observed in neurons cocultured with PMC for 18-24 h without stimulation was due to a proportion of PMC undergoing spontaneous activation. These changes in neuronal physiology are attributed to the action of substances released from the mast cells. This coculture model offers the means to study the cellular interactions involved in neuroimmune communication.