BOTHROPIC ANTIVENOM (BjAv) EFFICACY ON MICROCIRCULATORY EFFECTS EVOKED BY Bothrops jararaca VENOM (BjV). INTRAVITAL MICROSCOPIC STUDY

Battellino, C.(1), Piazza, R.(2), Silva, A.M.M.(3), Cury, Y.(4), Farsky, S.H.P.(1,5)

Laboratórios de (1)Imunoquímica, (2)Microbiologia, (3)Imunopatologia, (4)Fisiopatologia do Instituto Butantan e (5)Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, USP, São Paulo, Brasil.

Introduction: I.v. administration of BjAv neutralises systemic effects but does not completely reverse the local reaction evoked by BjV. The mechanism involved in this inefficacy has not been already known. The aims of this work were: 1) to investigate the efficacy of BjAv  on effects evoked by BjV on microcirculatory network and 2) to determine the distribution of AvBt on systemic and microcirculatory network.

Methods: Internal spermatic fascia of Wistar rats was exposed to visualise the microcirculation vessels. AvBj  was i.v. injected (2.5 ml/kg) 15 min before, simultaneously or 15 after topical application of BjV (10 µg/10µl sterile saline). Control animals received equivalent amount of horse normal serum. AvBt was also fluorescein-isothiocyanate (FITC) labelled before injection to visualise the dynamic of its distribution on microcirculation. FITC-albumin labelled was i.v. injected to determine vascular permeability increase. Immunoenzimatic assay was carried out in rat serum to determine the clearance of AvBt.

Results: Data obtained showed that the three AvBj treatment protocols did not completely neutralise the local blood coagulation, vascular permeability, haemorrhage and leukocyte-endothelial interactions induced by topical application of BjV. Differently, in vitro incubation of AvBj/BjV previously to application on the microcirculatory network neutralised all effects. Images obtained after FITC-AvBt labelled injection showed that the AvBt remains inside the vessel until the rapid action of BjV. Also, the complete microcirculatory stasis induced by the venom impairs the AvBt distribution. ELISA assay showed that AvBt is present at the circulating blood until 4 hours after its application.

Conclusions: Our data show that AvBt has antibodies against toxins responsible for the local effects induced by  BjV and suggest  that AvBt does not completely reverse these effects because the interaction BjV/AvBt only takes place after BjV action. Also, the impaired microcirculation blood flow evoked by  BjV prevents the adequate AvBt distribution.

Financial support: FAPESP- 96/10315-1.

CORRESPONDENCE TO:

Sandra Helena Poliselli Farsky, Rua Tucumã 217 ap 101, São Paulo, SP, CEP: 01455-010, Brasil, Email: sfarsky@usp.br