Electrophysiological effects of a neurotoxin extracted from the skin of the Australian frog Pseudophryne coriacea.
1. The electrophysiological effects of a pumiliotoxin-B-like alkaloid extracted from the skin of the Australian frog Pseudophryne coriacea (PsC) have been studied in rat superior cervical ganglia at 37 degrees C. 2. PsC (50 mg/ml) elicits a broadening of the evoked compound action potential and, at rest, the appearance of spontaneous spike discharge at 10-20 Hz. Action potentials presumably originate far away from the soma, which is invaded in a typical IS-SD sequence. 3. The toxin effect is not related to any direct action on the preganglionic fibers of the sympathetic trunk, and does not involve synaptic mechanisms. 4. Two-electrode voltage-clamp experiments showed that the main properties of the major voltage-dependent ionic currents are apparently unaffected by the toxin, while the cell input resistance is considerably reduced. 5. The data are consistent with the hypothesis that PsC elicits a cationic permeability increase generating a pacemaker current in a region close to the cell soma.
Istituto di Fisiologia Generale dell'Università, Ferrara, Italy.
O
O
Sacchi
R
R
Bardoni
P C
PC
Magherini
O
O
Belluzzi
D000200:Action Potentials / Q000187:drug effects; D000470:Alkaloids / Q000302:isolation & purification* / Q000494:pharmacology; D000664:Amphibian Venoms; D000818:Animals; D001001:Anura; D004553:Electric Conductivity; D004594:Electrophysiology; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009498:Neurotoxins / Q000302:isolation & purification* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000737:chemistry*; D013569:Synapses / Q000187:drug effects / Q000502:physiology
D000470:Alkaloids; D000664:Amphibian Venoms; D009498:Neurotoxins