[Long-lasting afterhyperpolarization of sympathetic preganglionic neurons of neonate rat spinal cord slices].

Intracellular recordings of antidromically identified sympathetic preganglionic neurons (SPNs) were made in thoracolumbar spinal cord slices from neonate rats (7-16 days). In the SPNs population, a 7-20 mV long-lasting afterhyperpolarization (11-AHP) lasting for 1 to 10 s following spike potential could be recorded in part of the neurons and the 11-AHPs was usually preceded by a fast component lasting shorter than 400 ms. With decrease of membrane resistance during 11-AHP, membrane potential-dependent property was observed and the calculated reversal potential was -90 to -100 mV. The results indicate that the 11-AHPs are effective in the control of firing frequency of SPNs.