Poneratoxin, a novel peptide neurotoxin from the venom of the ant, Paraponera clavata.
1. At concentrations varying from 10(-8) to 10(-6) M synthetic poneratoxin (PoTX) is a strong, but very slowly acting agonist for smooth muscles and its blocks synaptic transmission in the insect CNS in a concentration-dependent manner and depolarizes giant interneurons. 2. However, in isolated dorsal unpaired median cells 10(-6) M PoTX causes only a reversible hyperpolarization of about 5 mV. 3. At concentrations from 10(-8) to 10(-6) M PoTX affects the electrical activity of isolated cockroach axons, as well as isolated frog and rat skeletal muscle fibres. 4. PoTX prolongs action potentials and induces slow automatic activity, due to a slow Na(+)-current activation at very negative values of potential and due to slow deactivation.
Department of Pharmacology, University of Amsterdam, The Netherlands.
T
T
Piek
A
A
Duval
B
B
Hue
H
H
Karst
B
B
Lapied
P
P
Mantel
T
T
Nakajima
M
M
Pelhate
J O
JO
Schmidt
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000862:Ant Venoms / Q000494:pharmacology*; D001369:Axons / Q000187:drug effects / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000187:drug effects / Q000502:physiology; D019476:Insect Proteins; D009130:Muscle, Smooth / Q000187:drug effects; D009498:Neurotoxins / Q000494:pharmacology*; D010526:Periplaneta; D011893:Rana esculenta; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects
D000862:Ant Venoms; D019476:Insect Proteins; D009498:Neurotoxins; C072588:poneratoxin