TY - JOUR
T1 - Neuromuscular effects of a toxic phospholipase-a2 isolated from venom of the solomon-island sea-snake laticauda-colubrina
AU - Rowan, E.G.
AU - Harvey, A.L.
AU - Tamiya, N.
PY - 1985
Y1 - 1985
N2 - A phospholipase A, (Lc PLA-BII) has an LDs0 value of 48 ng/g (i.v.) in mice. A homologous protein (Lc PLH) has no phospholipase or lethal activities. The neuromuscular activities of the Lc PLA-BII and Lc PLH were
tested on chick biventer cervicls and mouse hemidiaphragm preparations. At 5-20 ~g/ml, Lc PLA-EII depressed responses of the biventer cervlcis
preparation to nerve stimulation and also acetylchollne and carbachol responses, indicating a post-junctional effect. This was not observed at lower concentrations which still abolished responses to indirect
stimulation. Therefore, at these concentrations neuromuscular block was a prejunctional phenomenon. This anomaly may be due to contamination of the
phospholipase component by a postjunctlonal neurotoxin. There was little direct effect on muscle contractillty. Immediately after addition of the
toxin, a transient increase in twitch height was observed, and onset of neuromuscular block follOWed without a lag period. No contracture was observed. Lc PLA-BII reduced responses of mouse diaphragm preparations to
indirect stimulation after a lag period. Preceding the lag period a transient increase in twitch height was observed at all concentrations tested (0.1-5 ~g/ml). Interestingly, the lag period at each of theconcentrations tested was of similar duration.The homologue Lc PLH (5-20 ~g/ml) reduced the responses of the blventer cervicls preparation to indirect stimulation, abolished acetylcholine and
carbachol responses but had little effect on responses to KCI. At 20~g/ml, twitches were reduced by 50% after i00 minutes. No lag period was observed. When tested on indirectly stimulated mouse hemidiaphragms,
little effect was observed after 5 hours at 5-10 ~g/ml.
AB - A phospholipase A, (Lc PLA-BII) has an LDs0 value of 48 ng/g (i.v.) in mice. A homologous protein (Lc PLH) has no phospholipase or lethal activities. The neuromuscular activities of the Lc PLA-BII and Lc PLH were
tested on chick biventer cervicls and mouse hemidiaphragm preparations. At 5-20 ~g/ml, Lc PLA-EII depressed responses of the biventer cervlcis
preparation to nerve stimulation and also acetylchollne and carbachol responses, indicating a post-junctional effect. This was not observed at lower concentrations which still abolished responses to indirect
stimulation. Therefore, at these concentrations neuromuscular block was a prejunctional phenomenon. This anomaly may be due to contamination of the
phospholipase component by a postjunctlonal neurotoxin. There was little direct effect on muscle contractillty. Immediately after addition of the
toxin, a transient increase in twitch height was observed, and onset of neuromuscular block follOWed without a lag period. No contracture was observed. Lc PLA-BII reduced responses of mouse diaphragm preparations to
indirect stimulation after a lag period. Preceding the lag period a transient increase in twitch height was observed at all concentrations tested (0.1-5 ~g/ml). Interestingly, the lag period at each of theconcentrations tested was of similar duration.The homologue Lc PLH (5-20 ~g/ml) reduced the responses of the blventer cervicls preparation to indirect stimulation, abolished acetylcholine and
carbachol responses but had little effect on responses to KCI. At 20~g/ml, twitches were reduced by 50% after i00 minutes. No lag period was observed. When tested on indirectly stimulated mouse hemidiaphragms,
little effect was observed after 5 hours at 5-10 ~g/ml.
KW - latlcauda colubrina
KW - phosphollpase
KW - neuromuscular block
UR - http://dx.doi.org/10.1016/0041-0101(85)90313-7
U2 - 10.1016/0041-0101(85)90313-7
DO - 10.1016/0041-0101(85)90313-7
M3 - Article
VL - 23
SP - 606
EP - 606
JO - Toxicon
JF - Toxicon
SN - 0041-0101
IS - 4
ER -