Transforming growth factor‐β2 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 utilized to examine the ability of transforming growth factor‐β2 (TGFβ2) to alter voltage‐gated K + channel development. Whole‐cell patch clamp recordings were used to monitor changes in three separate K + currents: A rapidly inactivating A‐current (I Af ), a slowly inactivating A‐current (I As ), and a non‐inactivating current (I K ). Continuous TGFβ2 (10 ng/ml) treatment selectively altered the normal developmental decrease in I Af expression in SCG neurons, but did not significantly 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 TGFβ2 treated cultures remained near initial values (∼2.7‐fold higher than control). This difference remained even after 4 weeks of exposure. TGFβ2 did not appear to change the activation kinetics or voltage‐dependence of I Af . These findings indicate that TGFβ2 may play an important role in modulating the development of neuronal excitability by regulating the expression of voltage‐gated K + channels. J. Neurosci. Res. 49:475–484, 1997. © 1997 Wiley‐Liss, Inc.