Morphine blocks the Mesobuthus tamulus venom-induced augmentation of phenyldiguanide reflex and pulmonary edema in anesthetized rats

• Published in: Indian journal of pharmacology Vol. 48; no. 1; pp. 74 - 77
• Main Authors: Akella, Aparna, Tiwari, Anil K, Rai, Om P, Deshpande, Shripad B
• Format: Journal Article
• Language: English
• Published: India Medknow Publications and Media Pvt. Ltd 01.01.2016; Medknow Publications & Media Pvt. Ltd; Medknow Publications & Media Pvt Ltd
• Subjects: Animals; Biguanides - pharmacology; Edema; Female; Health aspects; Morphine; Morphine - pharmacology; Narcotics; Prevention; Pulmonary edema; Pulmonary Edema - chemically induced; Pulmonary Edema - prevention & control; Rats; Reflex - drug effects; Rodents; Scorpion Venoms - antagonists & inhibitors; Scorpion Venoms - toxicity; Scorpions; Venoms; J-reflex; Acute pulmonary edema; cardiac arrest; Indian red scorpion; opioids
• ISSN: 0253-7613; 1998-3751
• DOI: 10.4103/0253-7613.174560

Pulmonary edema, a manifestation of scorpion envenomation syndrome, is attributed to cardiogenic or noncardiogenic factors. Morphine is a drug used for cardiogenic pulmonary edema and its effect on Mesobuthus tamulus (MBT) venom-induced changes is not known. Therefore, we hypothesized that morphine blocks the MBT venom-induced augmentation of phenyldiguanide (PDG) reflex and pulmonary edema. Experiments were performed on anesthetized adult female rats. Trachea and jugular vein were cannulated, and the electrocardiographic potentials were recorded by connecting needle electrodes in limb lead II configuration. PDG (10 ΅g/kg, IV, bolus injection) responses were elicited by bolus injection initially, after saline/morphine (1 mg/kg) and after injecting MBT venom (100 μg/kg). The time-response area of the PDG-induced bradycardiac response after treatment was calculated as % of the initial PDG response area. At the end of experiments, lungs were excised for determination of pulmonary water content. PDG produced bradycardiac response that lasted for >60 s. MBT venom augmented the PDG reflex response by 2.5 times. In morphine pretreated group, augmentation of bradycardiac response induced by MBT venom was absent. MBT venom increased the pulmonary water content, and the increase was absent in morphine pretreated animals. The results reveal that morphine prevents the MBT venom-induced augmentation of PDG reflex response and pulmonary edema. Thus, morphine can be useful in scorpion envenomation syndrome associated with pulmonary edema.