Pulmonary oedema producing toxin from Mesobuthus tamulus venom augments cardio-respiratory reflexes through B2 kinin receptors.
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Date
2014-10
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Abstract
The current study was undertaken to compare the effects of pulmonary oedema producing toxin (PO-Tx)
isolated from Mesobuthus tamulus venom on cardio-respiratory reflexes with exogenously administered
bradykinin (BK) and to delineate the type of BK receptors mediating these responses. Jugular venous
injection of phenyldiguanide (PDG) in anaesthetized rats produced reflex bradycardia, hypotension and
apnoea. The PDG-induced reflex was augmented (two folds) by PO-Tx. The pulmonary water content in POTx
treated group was also increased. The PO-Tx-induced reflex changes as well as pulmonary oedema were
blocked by Hoe-140 implicating the involvement of B2 kinin receptors. Exogenous BK also produced
augmentation (two folds) of the PDG-induced reflexes and increased the pulmonary water content. The BKinduced
augmentation was blocked by pre-treatment with des-Arg10 Hoe 140 (a B1 receptor antagonist) and
Hoe 140 (B2 receptor antagonist). However, these antagonists did not prevent the development of BK-induced
pulmonary oedema. Present results indicate that PO-Tx augmented the PDG-induced reflex responses
similar to BK and the PO-Tx induced augmentation of reflexes is mediated through B2 receptors.
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Alex Anitha B, Akella Aparna, Tiwari Anil K, Deshpande Shripad B. Pulmonary oedema producing toxin from Mesobuthus tamulus venom augments cardio-respiratory reflexes through B2 kinin receptors. Indian Journal of Physiology and Pharmacology. 2014 Oct-Dec ; 58 (4) : 312-318.