Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q96S42 (nodal)
 22,877 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was undertaken to evaluate the role of Na(+)/K(+) pump dysfunction in the development of diabetic neuropathy (DN). Nerve excitability techniques, which provide information about membrane potential and axonal ion channel function, were undertaken in 15 patients with established DN and in 10 patients with diabetes who had no evidence of neuropathy (DWN). Excitability parameters were recorded at baseline, and then before and after 1 min of maximal voluntary contraction (MVC) of abductor pollicis brevis. Compared to controls, CMAP amplitude was significantly decreased in DN patients with associated reductions in strength-duration time constant and refractoriness, consistent with a reduction in nodal Na(+) conductances. Following MVC for 1 min, there was an increase in normalized threshold in all diabetic patients and controls, consistent with axonal hyperpolarization. When compared to control values, the increase in threshold following MVC was significantly less in DN patients (DN group 13.1 +/- 2.2%; controls 20.4 +/- 1.9%; P < 0.05) and the rate of recovery was slower (P < 0.01). In DWN patients, CMAP amplitude was preserved, and excitability values following MVC were not significantly different to control values. The reduced threshold change and slower recovery in DN patients following MVC are likely to be secondary to Na(+)/K(+) pump dysfunction. Alteration in Na(+)/K(+) pump function, coupled with reductions in nodal Na(+) currents, may be sufficient to trigger conduction failure in DN patients and are likely to contribute to the clinical symptoms of weakness and fatigue.
 ...
PMID:Activity-dependent excitability changes suggest Na+/K+ pump dysfunction in diabetic neuropathy. 1836 98

Patients with peripheral neuropathy frequently suffer from positive sensory (pain and paresthesias) and motor (muscle cramping) symptoms even in the recovery phase of the disease. To investigate the pathophysiology of increased axonal excitability in peripheral nerve regeneration, we assessed the temporal and spatial expression of voltage-gated Na(+) channels as well as nodal persistent Na(+) currents in a mouse model of Wallerian degeneration. Crushed sciatic nerves of 8-week-old C57/BL6J male mice underwent complete Wallerian degeneration at 1 week. Two weeks after crush, there was a prominent increase in the number of Na(+) channel clusters per unit area, and binary or broad Na(+) channel clusters were frequently found. Excess Na(+) channel clusters were retained up to 20 weeks post-injury. Excitability testing using latent addition suggested that nodal persistent Na(+) currents markedly increased beginning at week 3, and remained through week 10. These results suggest that axonal regeneration is associated with persistently increased axonal excitability resulting from increases in the number and conductance of Na(+) channels.
 ...
PMID:Changes in Na(+) channel expression and nodal persistent Na(+) currents associated with peripheral nerve regeneration in mice. 1850 10

Excitability of regenerated fibers remains impaired due to changes in both passive cable properties and alterations in the voltage-dependent membrane function. These abnormalities were studied by mathematical modeling in human regenerated nerves and experimental studies in mice. In three adult male patients with surgically repaired complete injuries of peripheral nerves of the arm 22 months-26 years prior to investigation, deviation of excitability measures was explained by a hyperpolarizing shift in the resting membrane potential and an increase in the passive 'Barrett and Barrett' conductance (GBB) bridging the nodal and internodal compartments. These changes were associated with an increase in the 'fast' K(+) conductance and the inward rectifier conductance (GH). Similar changes were found in regenerated mouse tibial motor axons at 1 month after a sciatic crush lesion. During the first 5 months of regeneration, GH showed partial recovery, which paralleled that in GBB. The internodal length remained one-third of normal. Excitability abnormalities could be reversed by the energy-dependent Na(+)/K(+) pump blocker ouabain resulting in membrane depolarization. Stressing the Na(+) pumping system during a strenuous activity protocol triggered partial Wallerian degeneration in regenerated nerves but not in control nerves from age-matched mice. The current data suggest that the nodal voltage-gated ion channel machinery is restored in regenerated axons, although the electrical separation from the internodal compartment remains compromised. Due to the persistent increase in number of nodes, the increased activity-dependent Na(+) influx could lead to hyperactivity of the Na(+)/K(+) pump resulting in membrane hyperpolarization and neurotoxic energy insufficiency during strenuous activity.
 ...
PMID:Persistent alterations in active and passive electrical membrane properties of regenerated nerve fibers of man and mice. 2643 9