TRANSFORMING GROWTH-FACTOR-BETA-2 SELECTIVELY ALTERS THE DEVELOPMENTAL EXPRESSION OF THE FAST TRANSIENT A-CURRENT IN CULTURED RAT SUPERIOR CERVICAL-GANGLION NEURONS

Cultures of neonatal rat superior cervical ganglion (SCG) were utilize d to examine the ability of transforming growth factor-beta 2 (TGF bet a 2) to alter voltage-gated K+ channel development, Whole-cell patch c lamp recordings were used to monitor changes in three separate K+ curr ents: A rapidly inactivating A-current (I-Af), a slowly inactivating A -current (I-As), and a non-inactivating current (I-K). Continuous TGF beta 2 (10 ng/ml) treatment selectively altered the normal development al decrease in I-Af expression in SCG neurons, but did not significant ly change I-As or I-K expression, After 2 weeks of treatment, the mean I-Af current density in control cultures had decreased 67%, while the I-Af current density in TGF beta 2 treated cultures remained near ini tial values (similar to 2.7-fold higher than control), This difference remained even after 4 weeks of exposure, TGF beta 2 did not appear to change the activation kinetics or voltage-dependence of I-Af. These f indings indicate that TGF beta 2 may play an important role in modulat ing the development of neuronal excitability by regulating the express ion of voltage-gated K+ channels. (C) 1997 Wiley-Liss, Inc.