Ionic currents underlying rhythmic bursting of ventral mossy cells in the developing XXXX dentate gyrus.

@entity19 @entity1022 @entity1372 @entity5166 @entity72439 @entity3174 @entity460
The electrophysiological properties of mossy cells were examined in developing @entity19 hippocampal slices using whole-cell patch-clamp techniques, with particular reference to the dorsoventral difference. Dorsal mossy cells exhibited a higher spontaneous excitatory postsynaptic potential (EPSP) frequency and larger maximal EPSP amplitude than ventral mossy cells. On the other hand, the blockade of synaptic inputs with glutamatergic and GABAergic antagonists disclosed a remarkable dorsoventral difference in the intrinsic activity: none (0/27) of the dorsal mossy cells showed intrinsic bursting, whereas the majority (35/47) of the ventral mossy cells exhibited intrinsic rhythmic bursting. To characterize the ionic currents underlying the rhythmic bursting of mossy cells, we used somatic voltage-clamp recordings in the subthreshold voltage range. Ventral bursting cells possessed both hyperpolarization-activated current (Ih) and persistent @entity1372 current ( @entity72439 ), whereas dorsal and ventral nonbursting cells possessed Ih but no @entity72439 . Blockade of Ih with @entity5166 did not affect the intrinsic bursting of ventral mossy cells. In contrast, the blockade of @entity72439 with @entity1022 or @entity3174 established a stable subthreshold membrane potential in ventral bursting cells. The current-voltage curve of ventral bursting cells showed a region of @entity1022 -sensitive negative slope conductance between -55 mV and a spike threshold ( approximately -45 mV). On the other hand, no subthreshold @entity460 conductances played a significant role in the intrinsic bursting of ventral mossy cells. These observations demonstrate the heterogeneous electrophysiological properties of hilar mossy cells, and suggest that the subthreshold @entity72439 plays a major role in the intrinsic rhythmic bursting of ventral mossy cells.
