Saxitoxin, tetrodotoxin and the metabolism and cation fluxes in isolated cerebral tissues

PSP appears to be a relatively common illness in eastern Canada, with 200 reported poisonings and 23 deaths since 1880. Parts of the Hay of Fundy and the lower estuary of the St . Lawrence River are the most often implicated areas . The majority of poisonings aoarr between June and September and are associated with the abundance of the marine dhnoflagellate Gonyau/ax lamar~nsis . In cultures, this animal synthesizes a potent endotoxin which appears to be very similar in its chemical and pharmacological properties to the toxin extracted from poisonous shellfish. Although 14 spedea of shellfish have been shown to be toxic, soft-shell clams and blue mussels accounted for approximately 90 per cent of all poisonings in the area studied. Blue mussels accumulate the largest amounts of toxin in the shortest time . The clinical problem of PSP is described. It would have certainly been of value to the physician if the authors had presented one or two classical cases, rather than quoting from other works, the authors of which have usually compiled symptoms and signs without the advantage of having seen a case . However, the authors' sequence and division of clinical manifestations is a most practical contribution for the physidan. The monograph contains a number of excellent maps showing the distribution of toxic shellfish and poisonings, tables on the inddeace of reported cases of poisoning and on other related data. There are photomicrographs of G. lamarenris and aeva~al plates showing the various shellfish usually affected in eastern Canada . The authors have added some timely oommemts on various control programs and an interesting page on folklore and traditional belid's . There are dose to 100 references noted in the bibliography . This is an excellent monograph, not only on the subject of PSP in eastern Canada but on the problem of shellfish poisoning throughout the world. It is the finest epidemiological review for aßy of the endemic areas that,has yet appoared . The paper will be of particular interest to public health workers and physidans, as well as fishery biologists . F.E.R.

Burr, R. J, and Tasvox, A. ß. (Department of Pharmacology, University of California, San Fransisoo Medical Center, San Frandtco, Califorma 94122). Saxitoxin, tetrodotoxin and the m~abolism and cation ßuxes in isolated cerebral tissues. J Neyrochenr. ]9, 999 (1972) . Trns rat reports the metabolic response (lactate production) and the radiatribution of ions (Na+, g+~ ~.+) ~ rot brain slices during electrical stimulation, and the modification of these effects by saxitoxin and tetrodotoxin. Saxitoxin inhibited the glyoolydc activity and the Na+ and K+ fluxes in similar fashion to tetrodotoxin but was more potent. However, in low Ca'+ media, tetrodotoxin showed a similar inhibition of lactate production but saxitoxin failed to affect this parametce. The effects of the toxins on Ca'+ influx were also dissimilar, tetrodotoxin, but not sexitoxin, inhibiting unstimulatod Ca'+ i~lux; stimulated Ca' influx was again inhibited by tetrodotoxin, but potmtiated by taxitoxin. These results are interpreted as implying that the glyoolytic activity of basin tissue is not influenced solely by Na+ entry but that external Cà'+ ma
W~r~a~.n, C. J. and Ev~rls, M. H. (A.R .C. Institute of Animal Physiology, Babraham, Cambridge, England) . A method for distinguishing Tetrodotoxin from Saxitoxin, by comparing their relative stabilities when heated in add solution. F.xperkxlfa 2g, 670, 1972 T~ rrn~enrr nwmtoxins Tetrodotoxin (TTX, from puffer fish, newts of genus Tarleha) and Saxitoxin (STX, from dinoflegellates of gurus Gor{yauJax) are di~wh to distinguish from each other by pharmacological means, since they have virtually the same mode of action. It is tl>crefore important to make use of some difference in a phyaicod>emical property as a tool for positive idmtißcation of the toxins. For this purpose, it is noted that strongly acid solutions of TTX (pH 1) rapidly lose toxicity at 100°C, while STX solutioro remain quite stable under these conditioro. Above pH 2 there is lest differmoe in the stabilities of the two toxins st IOO~C. Based on these observations, it is suggested that bioassay in the mouse of a suitable TOXlCON 1973 Vol . 11