No abstract available

[en] Crotoxin (Crtx) is the main toxin of South American rattlesnake (Crotalus durissus terrificus) venom. Research on antitumoral drugs has demonstrated the potential use of Crtx as tumour reducing agent. Tissue distribution studies are very important for clinical use and ^99mTc-labeling is a very convenient method for studies related to biodistribution. The aim of the present study was to label Crtx with ^99mTc keeping its biological activity for use in biodistribution and binding studies. High labeling yield was obtained using stannous chloride and sodium borohydride. Results demonstrated that biological activity of ^99mTc-Crtx was preserved and confirmed kidneys as the target organ. Biological activities of unlabeled and ^99mTc-labeled Crtx were evaluated after labeling. ^99mTc-Crtx can be a useful tool for imaging and binding studies. (author)

No abstract available

[en] The aim of this work was to use the binding assay of tritiated-dihydropyridine and radioiodinated Tx1, isolated from the Phoneutria nigriventer venom, in order to show the presence of Ca_v1 calcium channels on pituitary tumour cell (GH3). We showed that GH3 cells have specific sites for ¹²⁵I-Tx1, which are sensitive to nifedipine (∼20%). Reverse competition assay with ³H-PN200-110 (40% inhibition) and electrophysiological data (50% inhibition) suggest that Ca_v1 calcium channels are target sites for this toxin. To summarize, Tx1 binds to specific sites on GH3 cells and this interaction results in Ca_v1 calcium channel blockade. ³H-PN200-110 and ¹²⁵I-Tx1 binding assays proved to be useful tools to show the presence of calcium channels on GH3 cells. (author)