The potent excitatory effect of a novel polypeptide, anthopleurin-B, isolated from a sea anemone (Anthopleura xanthogrammica) on the frog spinal cord
Kudo, Y.; Shibata, S.
Journal of Pharmacology and Experimental Therapeutics 214(2): 443-448
1980
ISSN/ISBN: 0022-3565 PMID: 6156238 Document Number: 165278
The effect of a novel polypeptide, anthopleurin-B (AP-B), isolated from a sea anemone (A. xanthogrammica) was studied on the isolated, intra-arterially perfused spinal cord of the bullfrog and was compared with those of 3 other polypeptides isolated from sea anemones [anthopleurin-A (AP-A), anthopleurin-C (AP-C) and neurotoxin II of Anemonia sulcata (ATX-II)]. AP-B (10-9-10-7 M) caused a marked augmentation of the ventral and dorsal root potentials induced by the stimulation of the dorsal root, but AP-A, AP-C and ATX-II, even at a concentration of 10-7 M, showed no apparent effect. At a higher concentration of 10-6 M, the polypeptides caused a depolarization in both ventral and dorsal roots, but had no excitatory actions on the root potentials. AP-B markedly prolonged the half-decay time of the excitatory postsynaptic potential and elevated the membrane resistance, but had no effect on the duration of motoneuronal action potentials. AP-B facilitated the depolarization induced by L-glutamate or substance-P in Ca2+-free, Mg2+ (3.6 mM) Ringer solution. The excitatory action of Ap-B was much greater in low Ca2+ media (0.9 mM) than in high Ca2+ media (3.6 mM). AP-B may act on the subsynaptic membrane to make it more sensitive to neurotransmitters and the interaction between AP-B and Ca2+ on the neuronal membrane may play a significant role on the mode of its action.