Activation of neurokinin 3 receptor increases Na(v)1.9 current in enteric neurons.

The intrinsic primary afferent neurons (IPANs) of the guinea pig enteric nervous system express Na(v)1.9 sodium channels that produce a persistent TTX-resistant current having a low activation threshold and slow gating kinetics. These neurons receive slow EPSPs induced mainly by the activation of neurokinin 3 receptors (NK3r).

Selective expression of a persistent tetrodotoxin-resistant Na+ current and NaV1.9 subunit in myenteric sensory neurons.

Voltage-gated Na(+) currents play critical roles in shaping electrogenesis in neurons. Here, we have identified a TTX-resistant Na(+) current (TTX-R I(Na)) in duodenum myenteric neurons of guinea pig and rat and have sought evidence regarding the molecular identity of the channel producing this current from the expression of Na(+) channel alpha subunits and the biophysical and pharmacological properties of TTX-R I(Na). Whole-cell patch-clamp recording from in situ neurons revealed the presence of a voltage-gated Na(+) current that was highly resistant to TTX (IC(50), approximately 200 microm) and selectively distributed in myenteric sensory neurons but not in interneurons and motor neurons.

Myelin basic protein-reactive T cells induce conduction failure in vivo but not in vitro.

The ability of myelin basic protein (MBP)-reactive T cells to induce conduction failure was investigated and. With the model, somatosensory evoked potentials (SEP) were recorded before and during adoptively transferred experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Maximum amplitude SEP were reached within 15 min of anesthesia.

Controlling the excitability of IPANs: a possible route to therapeutics.

Recent studies have shown that intrinsic primary afferent neurons (IPANs) express a much larger range of ionic currents than non-sensory neurons of the enteric nervous system. These ionic currents can be modulated by neurotransmitters that are synaptically released onto the soma (unlike cranial and spinal sensory neurons). The membrane receptors and ionic channels that are involved in the sensory transduction processes of IPANS are beginning to be defined.

Effects of K+ channel blockers on developing rat myelinated CNS axons: identification of four types of K+ channels.

Four blockers of voltage-gated potassium channels (Kv channels) were tested on the compound action potentials (CAPs) of rat optic nerves in an attempt to determine the regulation of Kv channel expression during the process of myelination. Before myelination occurred, 4-aminopyridine (4-AP) increased the amplitude, duration, and refractory period of the CAPs. On the basis of their pharmacological sensitivity, 4-AP-sensitive channels were divided in two groups, the one sensitive to kaliotoxin (KTX), dendrotoxin-I (DTX-I), and 4-AP, and the other sensitive only to 4-AP.

Analysis of whole-cell currents by patch clamp of guinea-pig myenteric neurones in intact ganglia.

Whole-cell patch-clamp recordings taken from guinea-pig duodenal myenteric neurones within intact ganglia were used to determine the properties of S and AH neurones. Major currents that determine the states of AH neurones were identified and quantified. S neurones had resting potentials of -47 +/- 6 mV and input resistances (R(in)) of 713 +/- 49 MOmega at voltages ranging from -90 to -40 mV.