NGF-independent survival of postganglionic sympathetic neurons in neuronal-vascular smooth muscle cocultures

The present study tests the hypothesis that vascular cells promote the surv ival of postganglionic sympathetic neurons in the absence of nerve growth f actor (NGF). To test this hypothesis, neurons isolated from superior cervic al ganglia of 2- to 4-day-old rat pups were grown in the absence of NGF and in the absence and presence of vascular smooth muscle cells (VSM). Neurona l survival was assessed as a function of time in culture. At all time point s studied, VSM promoted the survival of the neurons. After 5 days in the ab sence of NGF, 7 +/- 2% of neurons survived in the absence and 28 +/- 7% sur vived in the presence of VSM. An endothelin receptor antagonist reduced neu ronal survival in cocultures grown in the absence of NGF. These data indica te that VSM produce factors other than NGF that promote the survival of cul tured postganglionic sympathetic neurons. The data also indicate that endot helin contributes to this effect and suggest that endothelin as well as oth er VSM-derived factors may play a role in the development of sympathetic in nervation to the vasculature.