Modification of nerve conduction in the rat by brevetoxin (PBTX-3)

1 Pages·1994·0.21 MB·

by  Christine E Purcell

586 MEMOIRSOFTHEQUEENSLANDMUSEUM
MODIFICATIONOFNERVECONDUCTIONINTHE tagonist experiments lignocaine (500|Ag/kg) was delivered
RAT BY BREVETOXIN (PBTX-3) Memoirs of the intravenously,over30minutes.
Queensland Museum 34(3): 586. 1994- Brevetoxins are PbTx-3 produced a significantincrease in both the mag-
lipid-solublepolycyclicethertoxinsisolatedfromthemarine nitudeanddurationofsupernormalitytothatofcontrol ner-
dinoflagellate Ptychodiscus brevis. The toxins PbTx-2 and ves. This toxin also increased the absolute and relative
PbTx-3bindtoaspecificreceptorsite(site5)onthevoltage- refractory periods and decreased the conduction velocity.
dependentsodiumchannel,asitesharedwithciguatoxin.This Lignocainereturnedtheseparameterstowardscontrolvalues.
studysetouttoexaminetheeffectsofPbTx-3andapossible These results demonstrate that PbTx-3 alters nerve con-
antagonistontheparametersofnerveconduction. ductionparametersofratsinasimilarwaytociguatoxin.Itis
Electrophysiological studies were carried out on the suggested that brevetoxin may provide a suitable model in
ventral coccygeal nerve of male Wistar rats. Prior to ex- further studies pertaining to possible therapeutic agents for
perimentationeachanimalwasanaesthetisedwithintramus- ciguaterapoisoning.
cular Leptan (420^1/kg). A Medelec MS92a electro-
myographyunitwasusedforrecordings. PbTx-3 (15^Lg/kg) Christine E. Pureed, John Cameron & Michael F. Capra,
was administered intravenously over 15 minutes. In an- SchoolofLifeScience,QueenslandUniversityofTechnology,
GPOBox2434,Brisbane4001 Queensland; 12April, 1994.
.
CIGUATERA RESEARCH - AN HISTORICAL While an extensive search for an algal food source or a
PERSPECTIVE. Memoirs of the Queensland Museum toxin precursor produced no useful leads, it gave rise to
34(3): 586. 1994:- Ciguatera research at the University of significant discoveries, most prominent among them of
Hawaiiwasinitiatedinthemid-1950'sby thelateProfessor palytoxin, which in time became a benchmark in marine
A.H. Banner, who formulated four principal objectives: 1, natural product chemistry, and indeed, in all of organic
What is the molecular structure ofthe toxin?2, What is the chemistry.
origin ofthe toxin? 3, Can a diagnostic test be devised that The first clue that ciguatoxin belonged to the structural
distinguishes toxic from nontoxic fish? 4, Can an effective typeofpolyethersdidnotcomefromsophisticatedinstrumen-
humantherapybefound? tation,butfromitsbehaviourinchromatographywhichparal-
Elucidationofthemolecularstructurewasofcentralcon- leled that of okadaic acid, a compound first isolated and
cernsincesuccesswiththeotherthreegoalswouldbegreatly characterized as a constituent ofa sponge and subsequently
enhanced,ordependon,aknowledgeofstructuralfeatures. identifiedasametaboliteofthedinoflagellateProrocentrum
Inadequate supplies of toxic fish, establishment of a lima.Interestingly,okadaicacidhaslowmammaliantoxicity
suitablebioassay, andtechnologyofthe60's madeforslow and has become an important probe in the study ofcellular
progress. Even afterthe discovery ofadinoflagellate as the regulation.
primarytoxinproducerin 1977,morayeelshadtoremainthe
solesourceoftoxin,sinceG.toxicusculturesyieldedonlythe Paul J. Scheuer, Department of Chemistry, University of
water-solublemaitotoxin,whichwasdistinctlydifferentfrom Hawaii at Manoa, Honolulu, HI 96822, U.S.A.; 12 April,
thelipid-solubleciguatoxinextractedfromcarnivorousfish. 1993.