Characterization of Bothrops jararaca snake venom effects on rat vas deferens
Sciani, J. M
The main compounds of Bothrops jararaca venom are serine peptidases, metallopeptidases and phospholipases A2. These enzymes cause several symptoms, as hemorrhage, coagulation disturbances, edema and myotoxicity. However, effects on smooth muscle are not clear yet. Previous studies in our laboratory have shown that Bothrops jararaca crude venom (CV) provokes contractions of rat vas deferens, followed by relaxation. The aim of this study was to characterize which components of Bothrops jararaca venom are responsible for contraction and if this reaction is neurogenic or myogenic. Vas deferens were isolated and mounted in an appropriated chamber containing continuously aerated nutritive solution at 37°C. Organs were electrically stimulated (5 Hz, 3 ms, 90 V, in trains of 10 s) during 60 minutes. Once established, fractions from 1 up to 6 (100 μg/mL), obtained by gel filtration chromatography (Sephacryl S-100 resin) were added. Before and after samples incubation, vas deferens was stimulated with KCl (80 mM). Using the same protocol, before adding to tissue, fractions were pre-incubated with EDTA (100 µM), a metallopeptidase inhibitor, or PMSF (100 µM), a serine peptidase inhibitor. Hoe 140 (100 nM), B2 receptor antagonist, also was incubated with vas deferens, before venom addition. Fractions 4, 5 and 6 did not cause significant effects on vas deferens, which excluded the phospholipase A2 action. Fraction 1 caused similar effects compared to CV, an increase of neurogenic and myogenic contractions, but did not inhibit any of them. The contractile effect was inhibited by PMSF and Hoe 140, indicating that serine peptidase and bradykinin are responsible by neurogenic and myogenic contraction, probably by bradykinin release by serine peptidases, from the vas deferens. KCl-induced contraction was not altered.(AU)
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