Effects caused by myotoxin I and myotoxin II from Bothrops moojeni venom in rat isolated kidney

Barbosa, P.S.F., Havt, A., Toyama, M.H.S., Martins, A.M.C., Nobre, A.C.L., Soares, T.F.C., Fonteles, M.C., Monteiro, H.S.A.

UNICAMP and Federal University of Ceará, UFC. 

Acute renal failure is one the most common systemic complications after snakebite, however, its pathogenesis remains obscure. In this study we evaluated the renal effects of B. moojeni myotoxins (Bmtx-I and BmtxII) in rat isolated perfused kidneys. The B. moojeni myotoxins were purified by ion-exchange chromatografy and reverse phase HPLC. Wistar rats (240 - 280 g) were anesthetized with sodium pentobarbitone (50 mg/kg, i.p.) and the right renal artery was cannulated as described by Fonteles et al., (Am. J. Physiol. 244, 235-346, 1983). Bothrops moojeni myotoxins (5 mg/mL) were added to the perfusion system 30 min after the beginning of each perfusion. The renal effects were compared with a control group (CG), analyzed by ANOVA (p< 0,05). Bmtx-I increased the perfusion pressure (CG₁₂₀ = 113.5 ± 0.833, Bmtx-I₁₂₀ = 169.2 ± 5,0), renal vascular resistance (CG₁₂₀ = 5.216 ± 0.16, Bmtx-I₁₂₀ = 7.60 ± 0.31), urinary flow (CG₁₂₀ = 0.150 ± 0.002, Bmtx-I₁₂₀ = 0.296 ± 0.037), and glomerular filtration rate (CG₁₂₀ = 0.617 ± 0.022, Bmtx-I₁₂₀ = 0886 ± 0.149). Sodium, potassium and chloride tubular transport (%TNa⁺, %TK⁺, %TCl^-) decreased after administration of Bmtx-I. Bmtx-II had no effect on renal physiology, except for a transient decrease in potassium tubular transport (CG₉₀ = 75.22 ± 1.41, Bmtx-II = 66.61 ± 2.29). In conclusion, BmTx-I may have exerted its renal effects by indirectly increasing calcium influx after damage to the cell membrane. Apparent inability of Bmtx-II to induce the renal effects similarly to Bmtx-I should be explained by the absence of the C-terminal lysine rich region in Bmtx-II.

Supported by: FUNCAP, FAPESP

CORRESPONDENCE TO:

Alexandre Havt, Rua Tenente Benévolo 1560 ap/802, Fortaleza, CE, CEP: 60160-210, Brasil, Email: havt@speeder.com.br