Activation of axonal Kv7 channels in human peripheral nerve by flupirtine but not placebo - therapeutic potential for peripheral neuropathies: results of a randomised controlled trial.

Background: Flupirtine is an analgesic with muscle-relaxing properties that activates Kv7 potassium channels. Kv7 channels are expressed along myelinated and unmyelinated peripheral axons where their activation is expected to reduce axonal excitability and potentially contribute to flupirtine's clinical profile.

Trial Design: To investigate the electrical excitability of peripheral myelinated axons following orally administered flupirtine, in-vitro experiments on isolated peripheral nerve segments were combined with a randomised, double-blind, placebo-controlled, phase I clinical trial (RCT).

Sea-anemone toxin ATX-II elicits A-fiber-dependent pain and enhances resurgent and persistent sodium currents in large sensory neurons.

Background: Gain-of-function mutations of the nociceptive voltage-gated sodium channel Nav1.7 lead to inherited pain syndromes, such as paroxysmal extreme pain disorder (PEPD). One characteristic of these mutations is slowed fast-inactivation kinetics, which may give rise to resurgent sodium currents.

Anticancer drug oxaliplatin induces acute cooling-aggravated neuropathy via sodium channel subtype Na(V)1.6-resurgent and persistent current.

Infusion of the chemotherapeutic agent oxaliplatin leads to an acute and a chronic form of peripheral neuropathy. Acute oxaliplatin neuropathy is characterized by sensory paresthesias and muscle cramps that are notably exacerbated by cooling. Painful dysesthesias are rarely reported for acute oxaliplatin neuropathy, whereas a common symptom of chronic oxaliplatin neuropathy is pain.

Sustained increase in the excitability of myelinated peripheral axons to depolarizing current is mediated by Nav1.6.

Changes in the excitability of peripheral myelinated axons in response to long-lasting subthreshold depolarizing or hyperpolarizing currents (threshold electrotonus) are used as a complementary electrophysiological parameter in the study of peripheral nerve diseases in people. However, the contribution made by various axonal ion channels to specific components of threshold electrotonus remains incompletely understood. In this study, we have recorded threshold electrotonus responses from isolated nerve segments of sural nerve from control and Scn8amed mice, which lack functional Nav1.

Enhancement of axonal potassium conductance reduces nerve hyperexcitability in an in vitro model of oxaliplatin-induced acute neuropathy.

Oxaliplatin is used in the chemotherapeutic treatment of malignant tumours. A common side effect of oxaliplatin is an acute peripheral neuropathy characterized by axonal hyperexcitability, which can be painful and is aggravated by exposure to cold. Electrophysiological studies on isolated segments of peripheral rodent nerve have been able to replicate oxaliplatin's effect on axonal hyperexcitability in vitro.

The Kv7 potassium channel activator flupirtine affects clinical excitability parameters of myelinated axons in isolated rat sural nerve.

Flupirtine is an activator of Kv7 (KCNQ/M) potassium channels that has found clinical use as an analgesic with muscle relaxant properties. Kv7 potassium channels are expressed in axonal membranes and pharmacological activation of these channels may restore abnormal nerve excitability. We have examined the effect of flupirtine on the electrical excitability of myelinated axons in isolated segments of rat sural nerve.

GABA increases electrical excitability in a subset of human unmyelinated peripheral axons.

Background: A proportion of small diameter primary sensory neurones innervating human skin are chemosensitive. They respond in a receptor dependent manner to chemical mediators of inflammation as well as naturally occurring algogens, thermogens and pruritogens. The neurotransmitter GABA is interesting in this respect because in animal models of neuropathic pain GABA pre-synaptically regulates nociceptive input to the spinal cord.

Modulation of remifentanil-induced analgesia and postinfusion hyperalgesia by parecoxib in humans.

Background: Numerous experimental and clinical studies suggest that brief opioid exposure can enhance pain sensitivity. It is suggested that spinal cyclooxygenase activity may contribute to the development and expression of opioid tolerance. The aim of the investigation was to determine analgesic and antihyperalgesic properties of the cyclooxygenase-2 inhibitor parecoxib on remifentanil-induced hypersensitivity in humans.