THE PURIFICATION OF Tityus ivic-nancor VENOM AND THE CHARACTERIZATION OF THE EFFECT OF THE SCORPION VENOMS OF THE Tityus GENUS ON RAT PANCREATIC PREPARATIONS

Tityus ivic-nancor VENOM AND THE CHARACTERIZATION OF THE EFFECT OF THE SCORPION VENOMS OF THE

Tityus GENUS ON RAT PANCREATIC PREPARATIONS.

R. López, G. D’Suze, C. M. Ruiz, F. Michelangeli, C. Sevcik .

Laboratorio de Neurofarmacología Celular, Laboratorio de Fisiología Gastrointestinal, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 21827, Caracas 1020A, D.F. Venezuela.

Envenomation caused by the scorpions Tityus discrepans (Td) and Tityus ivic-nancor (Tin) produces hyper-secretion of pancreatic enzymes in some cases leading to acute pancreatitis. Structural changes in the pancreas caused by Td venom have already been reported by D’Suze et al. in 1995. The chromatographic pattern of Tin venom (a new scorpion species described by González-Sponga in 1997) in sephadex G-50 produced three fractions: Tin I, Tin II, and Tin III (n=5) with a recovery percentage of 93%. Tin I represents 15%, Tin II 73%, and Tin III 11% of the total venom. The sub-fractions were obtained by high-performance liquid chromatography in a Vydac C4 semi-preparative column. The Tin I, Tin II, and Tin III fractions contain 30, 47 and 39 sub-fractions, respectively. The amylase release caused by Td and Tin venoms was studied in two preparations of rat pancreas (male Spraguey-Dowley rats weighing 150-200 g): a) an acinar preparation obtained by enzymatic digestion with collagenase A for 10 min; b) a lobular preparation obtained by dissection of the lobes (2 x 0.5 mm) in a pancreas perfused with Krebs solution supplemented with bovine albumin (buffered with HEPES, pH 7.4). The results in isolated acini when compared with those of the controls (11.96%±0.38) (n=5) showed that carbachol (10 µM) caused a 15.48%±1.48 release of amylase, while Td and Tin (20 µg/ml) induced an inhibitory release of 9.21%±1.11 and 7.37%±0.89, respectively. In contrast, results from the lobes incubated with venom (1 mg/ml) for 30 min point to increases in amylase secretion of 24%±3.7 in the presence of carbachol (10 µM) of 24%±3.9 with T.d crude venom, and of 25%±6 with Tin venom in comparison with the control (4%±1.2) (n=5). The presence of phospholypases in Tityus caripitensis (Tc), Td and Tin venoms was studied using thin layer chromatography. No differences were seen in the migratory patterns of the bands of the three venoms compared with those of the control. The concentration of intracellular Ca([Ca]i) is known to be involved in the secretion of acinus cells. Acini were then loaded with fura2 (a Caindicator) and the effect of Tin venom was confirmed. The addition of Tin venom (1 mg/ml) at the time of the measurement did not cause any change in [Ca]i, nor did it affect the later stimulation of carbachol (10 µM) and tapsigargine (3 µM), which increased [Ca]i. Acini incubated with Tin venom (1 mg/ml) for 30 min inhibited the effect of carbachol and reduced the effect of tapsigargine on the acini. Inhibiting the effect of carbachol depends on the venom concentration. Finally, permeability of the acini was evaluated with no difference being found between the controls and those incubated with venom.

This work has been partially financed by CONICIT, Project S1-95000722.

Publication Dates

• Publication in this collection
  16 Apr 1999
• Date of issue
  1999