Indian red scorpion (Buthus tamulus) venom-induced augmentation of cardiac reflexes is mediated through the mechanisms involving kinins in urethane anaesthetized rats.
The mechanism underlying the action of Indian red scorpion (Buthus tamulus; BT) venom on cardiac reflexes was examined in urethane anaesthetized adult albino rats of either sex. Intravenous injection of phenyldiguanide (PDG) produced reflex hypotension, bradycardia and apnea lasting for > 60 s. The PDG-induced reflex responses (blood pressure, heart rate and respiration) were augmented greatly (magnitude and time period) after exposure to BT venom (100 microg/kg, i.v., for 30 min). However, there were no great alterations in resting blood pressure, heart rate and respiratory rate. Pretreatment with kallikrein kinin inhibitor (aprotinin; 6000 kallikrein inactivating unit, i.v.) blocked the BT venom-induced augmentation of PDG reflex response. Further, pretreatment with indomethacin (prostaglandin synthetase inhibitor; 10 mg/kg) and heparin (1000 units/kg) also blocked the venom-induced potentiation of the reflex. Captopril (15 mg/kg), an agent known to increase endogenous kinins, also augmented the PDG induced-reflex to the same extent as in BT envenomed rats. The captopril-induced augmentation of the reflex was blocked by aprotinin and heparin, but not by indomethacin. The results indicate that kinins and prostaglandins are involved in the BT venom-induced augmentation of the cardiac reflexes.
Bagchi
S
S
Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Deshpande
S B
SB
D000700:Analgesics / Q000494:pharmacology*; D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D007611:Aprotinin / Q000494:pharmacology; D001645:Biguanides / Q000494:pharmacology; D002216:Captopril / Q000494:pharmacology; D004357:Drug Synergism; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D007705:Kinins / Q000187:drug effects*; D008297:Male; D051381:Rats; D012604:Scorpion Venoms / Q000037:antagonists & inhibitors / Q000633:toxicity*; D012605:Scorpions; D014361:Trypsin Inhibitors / Q000494:pharmacology*; D014520:Urethane
D000700:Analgesics; D000959:Antihypertensive Agents; D001645:Biguanides; D007705:Kinins; D012604:Scorpion Venoms; D014361:Trypsin Inhibitors; D014520:Urethane; D007611:Aprotinin; D002216:Captopril; C008846:phenyl biguanide