RESUMO
The effects of a fraction (T1) of Tityus serrulatus scorpion venom prepared by gel filtration on gastric emptying and small intestinal transit were investigated in male Wistar rats. Fasted animals were anesthetized with urethane, submitted to tracheal intubation and right jugular vein cannulation. Scorpion toxin (250 microg/kg) or saline was injected iv and 1 h later a bolus of saline (1.0 ml/100 g) labeled with 99m technetium-phytate (10 MBq) was administered by gavage. After 15 min, animals were sacrificed and the radioactivity remaining in the stomach was determined. Intestinal transit was evaluated by instillation of a technetium-labeled saline bolus (1.0 ml) through a cannula previously implanted in the duodenum. After 60 min, the progression of the marker throughout 7 consecutive gut segments was estimated by the geometric center method. Gastric retention of the liquid test meal in rats injected with scorpion toxin (median: 88%; range: 52-95%) was significantly higher (P<0.02) than in controls (54%; 21-76%), an effect which was not modified by gastric secretion blockade with ranitidine. The progression of the isotope marker throughout the small intestine was significantly slower (P<0.05) in rats treated with toxin (1.2; 1.0-2.5) than in control animals (2.3; 1.0-3.2). Inhibition of both gastric emptying and intestinal transit in rats injected with scorpion toxin suggests an increased resistance to aboral flow, which might be caused by abnormal neurotransmitter release or by the local effects of venom on smooth muscle cells.
Assuntos
Esvaziamento Gástrico/efeitos dos fármacos , Trânsito Gastrointestinal/efeitos dos fármacos , Venenos de Escorpião/farmacologia , Animais , Injeções Intraperitoneais , Intestino Delgado/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Estatísticas não ParamétricasRESUMO
The effects of a fraction (T1) of Tityus serrulatus scorpion venom prepared by gel filtration on gastric emptying and small intestinal transit were investigated in male Wistar rats. Fasted animals were anesthetized with urethane, submitted to tracheal intubation and right jugular vein cannulation. Scorpion toxin (250 Ág/kg) or saline was injected iv and 1 h later a bolus of saline (1.0 ml/100 g) labeled with 99m technetium-phytate (10 MBq) was administered by gavage. After 15 min, animals were sacrificed and the radioactivity remaining in the stomach was determined. Intestinal transit was evaluated by instillation of a technetium-labeled saline bolus (1.0 ml) through a cannula previously implanted in the duodenum. After 60 min, the progression of the marker throughout 7 consecutive gut segments was estimated by the geometric center method. Gastric retention of the liquid test meal in rats injected with scorpion toxin (median: 88 percent; range: 52-95 percent) was significantly higher (P<0.02) than in controls (54 percent; 21-76 percent), an effect which was not modified by gastric secretion blockade with ranitidine. The progression of the isotope marker throughout the small intestine was significantly slower (P<0.05) in rats treated with toxin (1.2; 1.0-2.5) than in control animals (2.3; 1.0-3.2). Inhibition of both gastric emptying and intestinal transit in rats injected with scorpion toxin suggests an increased resistance to aboral flow, which might be caused by abnormal neurotransmitter release or by the local effects of venom on smooth muscle cells
Assuntos
Animais , Ratos , Masculino , Esvaziamento Gástrico/efeitos dos fármacos , Trânsito Gastrointestinal/efeitos dos fármacos , Venenos de Escorpião/toxicidade , Injeções Intraperitoneais , Intestino Delgado/efeitos dos fármacos , Ratos Wistar , Estatísticas não ParamétricasRESUMO
In the present work the pH and arterial blood gases were measured in fasted and fed male albino rats, weighing 297 +/- 13 g, anaesthetized with urethane (1.4 g/kg, i.p.) before and after injection of T1 fraction from Titys serrulatus scorpion venom, during 60 min. Arterial blood samples were collected at 0, 5, 15, 30 and 60 min for pH, pCO2, pO2, bicarbonate and base-excess analysis. The data showed that the scorpion toxin induced a continuous drop in the blood pH along the time. Hypercapnia and hypoxemia peaking at 30 min and followed by a recovery towards normal values at 60 min were also observed. A pronounced decrease in the blood bicarbonate levels at 60 min and negative base-excess values along with time were evident at 60 min. The comparisons between fasted and fed animals have shown that in the last group the effects of scorpion toxin on the arterial blood gases were less pronounced. We conclude that T1 fraction of Tityus serrulatus scorpion venom induces in anaesthetized rats an acute respiratory acidosis followed by metabolic acidosis.