ASPECTS OF KINETIC AND BIODISTRIBUTION OF NEUROTOXIN FROM THE Phoneutria nigriventer VENOM

YONAMINE, C.M.(1), CAMILLO, M.A.P.(1), TRONCONE, L.R.P.(2)

(1)Laboratório de Biologia Molecular, IPEN-CNEN/SP, CP. 11049, São Paulo, SP, CEP 05422-970, Brazil, (2)Laboratório de Farmacologia, Instituto Butantan, São Paulo, SP, Brazil

The Phoneutria nigriventer spider venom contains innumerous neurotoxic peptides which interfere with voltage dependent ionic channels function. The present study was carried out with an isolated peptide from the venom. The molecular weight was 5290 daltons and induces priapism in mice at the dose of 5 mg/animal and may conduct to death. The objective was a kinetic and biodistribution study and aimed to contribute for a better understanding of its mechanism of action. The toxin was isolated after two steps: chromatography in SephadexG50 column with ammonium formiate buffer 100mM pH3.0 and, in sequence, in mRPC-C2C18 (Pharmacia) with water/TFA 0.1% and acetonitrile (grade 25-100% in 35min). The radioiodination was done by the method of modified cloramine T (Ribela et al., 1993). Mice BalbC, males, adults, fed with water and food ad libitum were kept in a room with natural cycle light and controlled temperature. The animals were endovenouslly administered and samples were collected after 5, 15 and 30min, 1, 2, 4, 7 and 24hours. The incorporated radioactivity was measured in blood, brain, heart, lung, liver, kidney-adrenal, spleen, stomach, testicle, intestine, muscle and thyroid. The blood measures were expressed as cpm/mL and statistically analyzed with the program GraphPad Prism, nonlinear regression, exponential model. For the organs the results were expressed as cpm/g of tissue. The results indicated that (a) there was a redistribution after 1hour, (b) hepatic metabolization with release of 125-Iodine, (c) it passed to be accumulated in the thyroid and (d) the renal clearence was the main elimination route.

CORRESPONDENCE TO:

YONAMINE, C.M., Laboratório de Biologia Molecular, IPEN-CNEN/SP, CP. 11049, São Paulo, SP, CEP 05422-970, Brazil, Email: mcamillo@net.ipen.br