RESUMO
Thalassophryne nattereri, popularly known as Niquim, is a venomous fish responsible for many accidents in fishermen in the Northeast of Brazil. The effects of T. nattereri venom on renal physiology has not been tested. Isolated kidneys from Wistar rats of 240-280 g weight were perfused with Krebs-Henseleit solution containing 6g% of previously dialyzed bovine serum albumin. The effects of Niquim venom were studied on the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), percent of sodium tubular transport (%TNa(+)), percent of potassium tubular transport (%TK(+)) and percent of chloride tubular transport (%TCl(-)). The venom of T. nattereri (0.3, 1.0, and 3.0 microg/ml) was always added to the system 30 minutes after the beginning of each experiment (n=6). All experiments were preceded by 30 minutes internal control period and an external control group, where kidneys were perfused with only Krebs-Henseleit solution. All three doses tested promoted increases in PP and RVR. The first two doses also increased GFR and UF. The higher dose promoted decreases in GFR, UF, %TNa(+), %TK(+), %TCl(-). In the treated groups we observed hyalin casts inside all tubules and proteinaceous material in the urinary space. We conclude that the effects resulted from niquim venom agents that promoted a direct effect in kidney cells causing the release of vasoactive factors.
Assuntos
Batracoidiformes , Venenos de Peixe/farmacologia , Rim/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Feminino , Taxa de Filtração Glomerular/efeitos dos fármacos , Taxa de Filtração Glomerular/fisiologia , Hialina/efeitos dos fármacos , Rim/patologia , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/patologia , Masculino , Perfusão , Ratos , Ratos Wistar , Urodinâmica/efeitos dos fármacos , Urodinâmica/fisiologia , Resistência Vascular/efeitos dos fármacos , Resistência Vascular/fisiologiaRESUMO
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 Bothrops moojeni venom and its myotoxins (Bmtx-I and BmtxII) in rat isolated perfused kidneys. The myotoxins were purified by ion-exchange chromatography and reverse phase HPLC. The whole venom (10 microg/ml) and myotoxins (5 microg/ml) were added to the perfusion system 30 min after the beginning of each perfusion. The renal effects were compared to a control group perfused with modified Krebs-Henseleit solution alone. B. moojeni venom decreased the perfusion pressure (PP), renal vascular resistance (RVR), and the percent sodium, potassium and chloride tubular transport (%TNa(+), %TK(+), %TCl(-)). In contrast, the venom increased the urinary flow (UF), glomerular filtration rate (GFR), and the sodium, potassium and chloride excretion (ENa(+), EK(+), ECl(-)). The renal effects of myotoxin I was very similar to those of the whole venom, but there was an increase rather than a decrease in the PP and RVR. Myotoxin II had no effect on renal physiology, except for a transient decrease in %TK(+). In conclusion, B. moojeni venom caused intense alterations in renal physiology, including a drop in vascular resistance associated with diuresis, natriuresis and kaliuresis. Bmtx-I had an opposite effect when compared to whole venom, showed in the parameters of PP and RVR. Bmtx-II had a mild effect in %TK(+). The apparent inability of Bmtx-II to induce the renal effect similarly to Bmtx-I should be explained by the absence in the Bmtx-II of the C-terminal lysine rich region.