Back to Search
Start Over
Pharmacological study of a new Asp49 phospholipase A(2) (Bbil-TX) isolated from Bothriopsis bilineata smargadina (forest viper) venom in vertebrate neuromuscular preparations.
- Source :
-
Toxicon : official journal of the International Society on Toxinology [Toxicon] 2013 Jul; Vol. 69, pp. 191-9. Date of Electronic Publication: 2013 Mar 26. - Publication Year :
- 2013
-
Abstract
- The neuromuscular activity of Bbil-TX, a PLA2 with catalytic activity isolated from Bothriopsis bilineata smargadina venom, was examined in chick biventer cervicis (BC) and mouse phrenic nerve-diaphragm (PND) preparations. In BC preparations, Bbil-TX (0.5-10 μg/ml) caused time- and concentration-dependent blockade that was not reversed by washing; the times for 50% blockade were 87 ± 7, 41 ± 7 and 19 ± 2 min (mean ± SEM; n = 4-6) for 1, 5 and 10 μg/ml, respectively. Muscle contractures to exogenous ACh and KCl were unaffected. The toxin (10 μg/ml) also did not affect the twitch-tension of directly-stimulated, curarized (10 μg/ml) BC preparations. However, Bbil-TX (10 μg/ml) produced mild morphological alterations (edematous and/or hyperchromic fibers) in BC; there was also a progressive release of CK (from 116 ± 17 IU/ml (basal) to 710 ± 91 IU/ml after 45 min). Bbil-TX (5 μg/ml)-induced blockade was markedly inhibited at 22-24 °C and pretreatment with p-bromophenacyl bromide (p-BPB) abolished the neuromuscular blockade. Bbil-TX (3-30 μg/ml, n = 4-6) caused partial time- and concentration-dependent blockade in PND preparations (52 ± 2% at the highest concentration). Bbil-TX (30 μg/ml) also markedly reduced the MEPPs frequency [from 26 ± 2.5 (basal) to 10 ± 1 after 60 min; n = 5; p < 0.05] and the quantal content [from 94 ± 14 (basal) to 24 ± 3 after 60 min; n = 5; p < 0.05] of PND preparations, but caused only minor depolarization of the membrane resting potential [from -80 ± 1 mV (basal) to -66 ± 2 mV after 120 min; n = 5; p < 0.05], with no significant change in the depolarizing response to exogenous carbachol. These results show that Bbil-TX is a presynaptic PLA2 that contributes to the neuromuscular blockade caused by B. b. smargadina venom.<br /> (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Subjects :
- Acetophenones metabolism
Animals
Bothrops
Carbachol pharmacology
Chickens
Diaphragm drug effects
Diaphragm metabolism
Male
Mice
Miniature Postsynaptic Potentials drug effects
Muscle Contraction drug effects
Muscle, Skeletal drug effects
Neuromuscular Junction drug effects
Phrenic Nerve drug effects
Phrenic Nerve metabolism
Neuromuscular Blockade
Phospholipases A2, Secretory pharmacology
Reptilian Proteins pharmacology
Viper Venoms chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1879-3150
- Volume :
- 69
- Database :
- MEDLINE
- Journal :
- Toxicon : official journal of the International Society on Toxinology
- Publication Type :
- Academic Journal
- Accession number :
- 23541434
- Full Text :
- https://doi.org/10.1016/j.toxicon.2013.03.006