The effects of polypeptide neurotoxin from Anemonia sulcata on nerve conduction in crayfish giant axons and on frog myelinated fibers have been analyzed. The main features of toxin action are the following: (i) the toxin acts at very low doses and its action is apparently irreversible. (ii) The toxin selectively affects the closing (inactivation) of the Na+ channel by slowing it down considerab...

Squid giant axons were internally perfused with tetrodotoxin and procaine, and excitability and electrical properties were studied by means of current-clamp and sucrose-gap voltage-clamp methods. Internally perfused tetrodotoxin was virtually without effect on the resting potential, the action potential, the early transient membrane ionic current, and the late steady-state membrane ionic curren...

there is strong evidence that two cerebral hemispheres are differentially involved in emotional memory and that amygdala is a key subcortical structure for emotional experience. the present research investigated the possible involvement of lateralization of basolateral amygdala (bla) and central amygdala (cea) in place avoidance memory. for this purpose, male long-evans rats (280-320 g) were im...

Some populations of the newt Taricha granulosa possess extremely highconcentrations of the neurotoxin tetrodotoxin (TTX). Tetrodotoxin is present in adult newts and their eggs, but has been assumed to be absent from the larval stage. We testedlarval and metamorphosed juveniles for the presence of TTX and evaluated thepalatability of these developmental stages to predatory dragonfly ...

To determine whether intramural nerves affect intestinal ion transport, we studied the effect of electrical field stimulation (EFS) on the movement of ions across isolated rabbit ileum. EFS increased the transmural electrical potential difference and the short circuit current (Isc), caused C1 secretion, and reduced conductance, but did not alter fluxes of Na or the residual current (JRnet). The...

By use of a sensitive in vitro microsuperfusion method, the cholinergic prsynaptic control of dopamine release was investigated in a prominent striosome (areas poor in acetylcholinesterase activity) located within the core of cat caudate nucleus and also in adjacent matrix area. The spontaneous release of [3H]dopamine continuously synthesized from [3H]tyrosine in the matrix area was found to be...

Jingzhaotoxin-I (JZTX-I), a 33-residue polypeptide, is derived from the Chinese tarantula Chilobrachys jing-zhao venom based on its ability to evidently increase the strength and the rate of vertebrate heartbeats. The toxin has three disulfide bonds with the linkage of I-IV, II-V, and III-VI that is a typical pattern found in inhibitor cystine knot molecules. Its cDNA determined by rapid amplif...

The effects of riluzole, a neuroprotective drug, on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in rat dorsal root ganglion neurons were studied using the whole-cell patch clamp technique. At the resting potential, riluzole preferentially blocked TTX-S sodium channels, whereas at more negative potentials, it blocked both types of sodium channels almost equa...