SUPPRESSION OF JAW-OPENING REFLEX OF RATS BY INTRA-ARTERIAL ADMINISTRATION OF BRADYKININ
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概要
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The suppressive effects of intra-arterial injection of bradykinin on jaw-opening reflex elicited by electrical stimulation of tooth pulp were investigated in lightly anesthetized rats. A thin polyethylene tube was inserted 5-6 mm into the saphenous artery in opposite direction of blood flow, and bradykinin solutions were injected into the artery at a constant flow rate (0.1-0.8 μg/sec) by a perista pump (SJ-1211, ATTO). Intra-arterial injection of bradykinin (0.2-0.8 μg/sec for 10-60 sec) rapidly induced a strong suppression of jaw-opening reflex elicited by tooth pulp stimulation at the intensity of 1.5×T (T: threshold for evoked digastric electromyogram) with an after-effect. The effectiveness depended on the flow rate of bradykinin injection: The longer period of bradykinin injection induced a longer suppression of jaw-opening reflex with a long lasting after-effect. Suppression of jaw-opening reflex induced by intra-arterial bradykinin injection was accelerated by occlusion of the femoral vein and completely abolished by transection of the femoral and the sciatic nerves. Intra-musclar injection of bradykinin also induced a potent suppression of jaw-opening reflex. Premedication with naloxone-HCl (2 mg/kg, intraperitoneal injection) partially antagonized the suppression of jaw-opening reflex induced by bradykinin injection (p<0.05 t-test). Intra-arterial injection of bradykinin caused a clear deprssion of blood pressure. However, this depression was independent of the suppression of jaw-opening reflex. These results suggest that the receptors responsive to intra-arterial injection of bradykinin, are supposed to be the polymodal receptors located in the deep structures, and participate in the process for suppression of jaw-opening reflex. The role of the polymodal receptors in acupuncture analgesia is also discussed.
- 名古屋市立大学の論文
- 1982-03-30