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1. The role of multiple potassium conductances in action potential repolarization and repetitive firing behavior of hypoglossal motoneurons was investigated using intracellular recording techniques in a brain stem slice preparation of the neonatal rat (0-15 days old). 2. The action potential was followed by two distinct afterhyperpolarizations (AHPs). The(More)
1. We used conventional intracellular recording techniques in 400-microns-thick slices from the brain stems of juvenile rats to investigate the action of norepinephrine (NE) on subthreshold and firing properties of hypoglossal motoneurons (HMs). 2. In recordings in current-clamp mode, 50 or 100 microM NE elicited a reversible depolarization accompanied by(More)
1. The role of calcium conductances in action potential generation and repetitive firing behavior of hypoglossal motoneurons (HMs) was investigated using intracellular recording and patch-clamp techniques in a brain stem slice preparation of neonatal rats (0-15 days old). 2. The action potential was followed by an afterdepolarization (ADP). The ADP was(More)
1. We investigated the effects of serotonin (5-hydroxytryptamine, 5-HT) on whole-cell barium currents through calcium channels in visualized neonatal rat hypoglossal motoneurones (HMs) in a thin brainstem slice preparation. 2. High voltage-activated (HVA) currents were elicited by depolarizing voltage steps from -70 to 0 mV; low voltage-activated (LVA)(More)
The effects of 5-HT on neonatal rat hypoglossal motoneurons (HMs) were studied in two in vitro slice preparations. Serotonin caused either reversible depolarization or the generation of an inward current (I5-HT) in every cell tested. I5-HT persisted after synaptic blockade. In most of the cells tested, the magnitude of I5-HT was independent of membrane(More)
Intracellular recording techniques were used to characterize changes that take place in rat hypoglossal motoneuronal excitability from early postnatal stages to adulthood. This study focused primarily on the first two weeks of postnatal life, when major changes in the maturation of the neuromuscular system take place. Neonatal hypoglossal motoneurons were(More)
1. Whole cell recordings of glutamatergic excitatory postsynaptic currents (EPSCs) evoked by electrical stimulation in the reticular formation were made from visualized hypoglossal motoneurons (HMs) in rat brain stem slices. 2. Carbachol, muscarine, or physostigmine reduced EPSC amplitude to 50 +/- 3%, 37 +/- 3%, and 54 +/- 7% (mean +/- SE) of control,(More)
Calcium influx through voltage-gated Ca2+ channels plays an important role in neuronal function. In a thin-slice preparation of neonatal rat hypoglossal motoneurons (HMs) we recorded Ba2+ currents through voltage-gated Ca2+ channels using the whole-cell configuration of the patch-clamp technique. We found that HMs have low-voltage-activated (LVA) and at(More)
1. The repetitive firing properties of neonatal and adult rat hypoglossal motoneurones (HMs) were investigated in a brainstem slice preparation. Neonatal HMs could be classified into two main groups: (1) neurones with a decrementing or adapting firing pattern (type D); exhibiting an early and a late phase; and (2) neurones with an incrementing or(More)
Previous studies have demonstrated multiple components of whole-cell calcium currents in hypoglossal motoneurons (HMs); HMs possess a low-voltage-activated (LVA) current and three types of high-voltage-activated (HVA) calcium currents based on sensitivity to omega-Aga IVA, omega-Conotoxin GVIA (omega-CgTx) and dihydropyridine analogs (DHPs). In the present(More)