The blockage of nerve activity by tetrodotoxin is unusually potent and specific. Our experiments were designed to distinguish whether its specificity of action was based on the identification of ions, the direction of cation flow, or differences in the early transient and late steady conductance pathways. Alkali cations were substituted for sodium in the sea water, bathing an "artificial node" ...

BACKGROUND Voltage-gated sodium channels (Nav) mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant (TTX-r) compared to other isoforms. Nav1.8 is highly expressed in dorsal root ganglion neurons and is functionally linked to nociception, but the sensitivity of TTX-r isoforms to inhaled anesthetics is unclear. M...

Although the importance of the vagal nerve in the pathogenesis of bronchial asthma has been reported, its precise contribution is still not fully understood. To shed more light on this area, we evaluated the possible contribution of vagal reflex in histamine-induced bronchoconstriction (HIB), and decided the site of action of histamine on the vagal nerve. For this purpose, we studied the effect...

The present study was carried out to determine the effect of dilazep, having an inhibitory effect on the Na+ channel, on the mechanical dysfunction and metabolic derangements induced by palmitoyl-L-carnitine in isolated rat heart and to compare the effect of dilazep with that of tetrodotoxin, a specific inhibitor of the Na+ channel. Rat hearts were perfused aerobically at a constant flow accord...

Tetrodotoxin is a neurotoxin that occurs in select species of the family Tetraodontidae (puffer fish). It causes paralysis and potentially death if ingested in sufficient quantities. In 2007, two individuals developed symptoms consistent with tetrodotoxin poisoning after ingesting home-cooked puffer fish purchased in Chicago. Both the Chicago retailer and the California supplier denied having s...

In neonatal spinal cord, we previously reported that exogenous angiotensin II (ANG II) acts at postsynaptic AT1 receptors to depolarize neonatal rat spinal ventral horn neurons in vitro. This study evaluated an associated increase in synaptic activity. Patch clamp recordings revealed that 38/81 thoracolumbar (T7-L5) motoneurons responded to bath applied ANG II (0.3-1 microM; 30 s) with a prolon...

The mechanisms involved in the long-lasting contraction induced by transmural stimulation were investigated in the isolated longitudinal muscle of the guinea-pig gastric corpus. Transmural stimulation induced an initial rapid contraction, a subsequent relaxation and a long-lasting contraction which was mimicked closely by the responses to noradrenaline and ATP. The rapid contraction was blocked...

Tetrodotoxin (TTX) is a potent neurotoxin that has been identified in a range of phylogenetically unrelated marine and terrestrial organisms. Tetrodotoxin was recently detected in New Zealand in Pleurobranchaea maculata (the grey side-gilled sea slug). From June 2010 to June 2011 wild specimens were collected from 10 locations around New Zealand. At one site (Narrow Neck Beach, Auckland) up to ...