Cytotoxic Action of Palytoxin in Cultured Aortic Smooth Muscle Cells

Abstract

Palytoxi'i (PaT.X) produced by coelenterate %pecies (genus Palythoa) is a potent marine toxin which induces irntense vasoconstriction and hemorrhage which contribute to lethality. The A7r5 clonal cell line, derived from fetal rat aonta, was i1sed to study the mechanism of PuTX toxicity. A7r5 cells exposed to nM concentrations of PaTX for 15 ran at room temperature followed by wash and Incubadion in cultuie medium mt 31C (k 30 min) developed swelling of endoplasmic recttilum, clumrping of cytoplasm, blebbing and shrinking of heterochromatin. 'lhes cells we-v nonviable as confirmed by inclusion cf trypan blue and release of LDH, The fSO for PArX cytotoxtely was 7.1 nM using the vital dye exclusioo a.id 4.1 nM for LDlt rmlease. Whole-cll patch clamp recordings from single A7r5 cells showed that PIX (3-10 nM, 11TC, 15 nin) dcpolarizel cells and increased membii lnductave t) Na * an " > 5.fold. Neither the PaTX-induced cytotoxicity nor the Inctas ionic vermabbdlity could be reversed by washing. 'However, prior incubation of ce~ls •ith ouabaln (10"M) or replacement of extacellular Na* with cholinel or K, after exposure to PaTX did reduce the cytoxicity. Removal ofextrceflular Cal' reduced PaTX-Inducod cytotoxtcity, but trtetmenit with 10 to 50 p*M verapamil did not, indicating that voltage-gated calcium channels were rtu involved. iIe awchanism of PaTX cytotoxicity in AWrS cells seems to involve intracellular 144' overload and can be duplicated by other Na' looophores such as nyqtatin. In light of the involvenwt of uth muscle in PaTX poisoning. AWr5 cell$ could serve at a useful modal to test specific dnrs for protoction against PaTX acuto and delayed ftoxiit. 94-08297 1*01 mnnnlll

Cite this paper

@inproceedings{DoxzonCytotoxicAO, title={Cytotoxic Action of Palytoxin in Cultured Aortic Smooth Muscle Cells}, author={Bryce F Doxzon and Sharad S. Deshpande} }