Scorpion (Buthus tamulus) venom toxicity on cardiopulmonary reflexes involves kinins via 5-HT3 receptor subtypes
The mechanisms underlying the action of Indian red scorpion Buthus tamulus (BT) venom-induced augmentation of cardiopulmonary reflexes elicited by intravenous injection of 5-HT were examined in urethane anaesthetized rats. The 5-HT produced a concentration-dependent increase in time-response area of bradycardiac response, with the responses at submaximal concentrations shifted to the left after exposure to BT venom (20 µg/kg, IV). Aprotinin (6000 kallikrein inactivating unit, IV) as such had no effect on 5-HT reflex responses (bradycardia, hypotension, and apnea), but blocked the venom-induced reflex augmentation. While ondansetron (10 µg/kg, IV) completely blocked the 5-HT reflex responses, these reappeared partially after venom exposure (20 µg/kg). Exposure to bradykinin (50 µg/kg, IV) for 30 min also augmented the 5-HT-induced reflex responses similar to venom. The bradykinin-induced augmentation was also blocked by ondansetron. Results indicate that the venom-induced augmentation of cardiopulmonary reflexes is mediated through kinins sensitizing 5-HT3 receptor subtypes.
| Main Authors: | , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Centro de Estudos de Venenos e Animais Peçonhentos - CEVAP, Universidade Estadual Paulista - UNESP
2001
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0104-79302001000100003 |
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