ROOM-TEMPERATURE CULTURE EXTENDS THE USEFUL LIFE OF ADULT NEURONS FOR VOLTAGE-CLAMP EXPERIMENTS

Isolated superior cervical ganglion (SCG) neurons were maintained in vitro at 22-degrees-C (22-degrees-C neurons) for up to 4 days in an effort to inhibit process outgrowth and thus extend the useful life of SCG neurons for voltage-clamp experiments. The neurons were viable after 4 days in vitro and remained roughly spherical whereas neurons maintained in vitro at 37-degrees-C (37-degrees-C neurons) developed extensive neurite processes after 2 days. The resting potential of 22-degrees-C neurons was more hyperpolarized and the action potential duration was reduced compared to acutely isolated neurons (acute neurons) or 37-degrees-C neurons. The steady state Na+ current activation and inactivation parameters of the acute and 22-degrees-C neurons were similar whereas the half activation voltage was hyperpolarized and the slope factor of inactivation was reduced for the 37-degrees-C neurons compared to the other two groups. The Na+ currents recorded from the 37-degrees-C neurons displayed obvious signs of poor voltage control which were not observed in the acute or 22-degrees-C neurons. The acetylcholine (ACh) sensitivity of both 22-degrees-C and 37-degrees-C neurons was significantly less than that of the acute neurons. This report demonstrates that room temperature culture of SCG neurons is a simple method which prevents process outgrowth and thus extends the useful life of the neurons for voltage-clamp experiments.