Effect of purified Russell's viper venom-factor X activator (RVV-X) on renal hemodynamics, renal functions, and coagulopathy in rats

Abstract

Acute renal failure (ARF) is the most frequent and a serious complication in victims of Russell's viper snakebites. Russell's viper venom-factor X activator (RVV-X) has been identified as a main procoagulant enzyme involving coagulopathy, which might be responsible for changes in renal hemodynamics and renal functions. Here, we purified RVV-X from crude Russell's viper venom to study renal hemodynamics, renal functions, intravascular clot, and histopathological changes in Sprague-Dawley rats. Changes in renal hemodynamics and renal functions were evaluated by measuring the mean arterial pressure, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), effective renal blood flow (ERBF), renal vascular resistance (RVR), and fractional excretion of electrolytes. After 10 min, rats receiving both crude venom and purified RVV-X decreased GFR, ERPF, and ERBF and increased RVR. These changes correlated to renal lesions. Along with the determination of intravascular clot, rats injected with purified RVV-X increased the average D-dimer level and reached a peak at 10 min, declined temporarily, and then reached another peak at 30 min. The temporal association between clots and renal dysfunction was observed in rats within 10 min after the injection of purified RVV-X. These findings suggested RVV-X as a major cause of renal failure through intravascular clotting in the renal microcirculation.

Fig. 1

Effects of purified RVV-X and crude venom at various concentrations on clotting time of human normal citrated plasma using the activated partial thromboplastin time assay. The results are expressed as mean + SD (n = 3). An asterisk (*) indicates statistic significance compared with the negative control plasma at P < 0.05. Their significance was analyzed by the student’s t-test. The normal plasma negative control was citrated human plasma reconstituted with only CaCl₂. Factor X deficient plasma negative control was factor X deficient human plasma reconstituted with only CaCl₂. The positive control was normal citrated or factor X deficient human plasma activated with cephalin (Instrumentation Laboratory Company) and 0.025 M CaCl₂.

Fig. 2

Average D-dimer levels in each group of rats at various times. The control group consisted of rats given only normal saline. The results are expressed as mean ± SD (n = 6). An asterisk (*) indicates statistic significance compared with the control group at P < 0.05. Their significance was analyzed by ANOVA using LSD as post hoc test at P < 0.05. A long dashed line indicates the D-dimer cut-off level at 0.3 mg/L.

Fig. 3

Peripheral blood films (100× magnification) of rats 3 h after injections of (a) crude venom, (b) purified RVV-X, (c) RV antivenom plus purified RVV-X, and (d) normal saline. Blood films were stained with Wright’s stain. The arrow indicates schistocytes.

Fig. 4

Histological sections of kidneys stained with hematoxylin and eosin (20× magnification) of rats 3 h after injections of (a) crude venom, (b) purified RVV-X, (c) RV antivenom plus purified RVV-X, and (d) normal saline. The arrow indicates the fibrin thrombi.

Fig. 5

Histological sections of lungs stained with hematoxylin and eosin (20× magnification) of rats 3 h after injections of (a) crude venom, (b) purified RVV-X, (c) RV antivenom plus purified RVV-X, and (d) normal saline. The arrow indicates inflammatory cell infiltration and hemorrhage, and vasculitis.