We studied the effect of pulsed ultrasound therapy (UST) and antibothropic polyvalent antivenom (PAV) on the regeneration of mouse extensor digitorum longus muscle following damage by Bothrops jararacussu venom. Animals (Swiss male and female mice weighing 25.0 ± 5.0 g; 5 animals per group) received a perimuscular injection of venom (1 mg/kg) and treatment with UST was started 1 h later (1 min/day, 3 MHz, 0.3 W/cm², pulsed mode). Three and 28 days after injection, muscles were dissected and processed for light microscopy. The venom caused complete degeneration of muscle fibers. UST alone and combined with PAV (1.0 mL/kg) partially protected these fibers, whereas muscles receiving no treatment showed disorganized fascicules and fibers with reduced diameter. Treatment with UST and PAV decreased the effects of the venom on creatine kinase content and motor activity (approximately 75 and 48%, respectively). Sonication of the venom solution immediately before application decreased the in vivo and ex vivo myotoxic activities (approximately 60 and 50%, respectively). The present data show that UST counteracts some effects of B. jararacussu venom, causing structural and functional improvement of the regenerated muscle after venom injury.

The effect of dose and volume of a perimuscular injection of Bothrops jararacussu venom on myonecrosis of skeletal muscle was studied in mice. An increase of the venom dose (0.25 to 2.0 µg/g) at a given volume (50 µl) resulted in an increase in plasma creatine kinase (CK) levels 2 h after injection. Plasma CK activity increased from the basal level of 129.27 ± 11.83 (N = 20) to 2392.80 ± 709.43 IU/l (N = 4) for the 1.0 µg/g dose. Histological analysis of extensor digitorum longus muscle 4 h after injection showed lesion of peripheral muscle fibers, disorganization of the bundles or the complete degeneration of muscle fibers. These lesions were more extensive when higher doses were injected. Furthermore, an increase in volume (12.5 to 100 µl) by dilution of a given dose (0.5 µg/g) also increased plasma CK levels from 482.31 ± 122.79 to 919.07 ± 133.33 IU/l (N = 4), respectively. These results indicate that care should be taken to standardize volumes and sites of venom injections.

We investigated the protective effect of suramin, an enzyme inhibitor and an uncoupler of G protein from receptors, on the myotoxic activity in mice of different crotalid snake venoms (A.c. laticinctus, C.v. viridis, C.d. terrificus, B. jararacussu, B. moojeni, B. alternatus, B. jararaca, L. muta). Myotoxicity was evaluated in vivo by injecting im the venoms (0.5 or 1.0 mg/kg) dissolved in physiological saline solution (0.1 ml) and measuring plasma creatine kinase (CK) activity. Two experimental approaches were used in mice (N = 5 for each group). In protocol A, 1 mg of each venom was incubated with 1.0 mg suramin (15 min, 37ºC, in vitro), and then injected im into the mice at a dose of 1.0 mg/kg (in vivo). In protocol B, venoms, 1.0 mg/kg, were injected im 15 min prior to suramin (1.0 mg/kg, iv). Before and 2 h after the im injection blood was collected by orbital puncture. Plasma was separated and stored at 4ºC for determination of CK activity using a diagnostic kit from Sigma. Preincubation of some venoms (C.v. viridis, A.c. laticinctus, C.d. terrificus and B. jararacussu) with suramin reduced (37-76%) the increase in plasma CK, except for B. alternatus, B. jararaca or L. muta venoms. Injection of suramin after the venom partially protected (34-51%) against the myotoxicity of B. jararacussu, A.c. laticinctus and C.d. terrificus venom, and did not protect against C.v. viridis, L. muta, B. moojeni, B. alternatus or B. jararaca venoms. These results show that suramin has an antimyotoxic effect against some, but not all the North and South American crotalid snake venoms studied here.