2026-03-10T12:26:45Z https://mdu.repo.nii.ac.jp/oai

oai:mdu.repo.nii.ac.jp:00001148 2023-06-19T08:20:54Z 1:46:80

カエル緊張性顎反射の筋運動制御 Motor Control of a Tonic Jaw Reflex in the Frog 鈴木, 宏和 運動単位 緊張性顎反射 鼻孔閉鎖反射 カエル application/pdf In order to characterize the types of motor units operating upon tonic jaw reflexes in the frog, the properties of the jaw muscles operating upon the nostril-closing reflex were examined histochemically and physiologically. In addition, the properties of motoneurons were examined by the firing pattern, firing rate, duration and some other characteristics of their efferent neural discharges during the reflex. The results are as follows: (1) Muscular contractions during the reflex were basically tonic, but these were sometimes accompanied by phasic contractions. (2) Histochemistry of myofibrillar ATPase and succinic dehydrogenase (SDHase) activities revealed that the nostril-closing (submental, submaxillary, masseter and pterygoid) muscles contain at least two types of muscle fibers. One type exhibited high alkaline-stable myosin ATPase and low SDHase activities, and the other type exhibited low alkaline-stable myosin ATPase and high SDHase activities. Muscle fibers with acid-stable myosin ATPase activity were prevalent in the pterygoid muscle, scarce in the submental and masseter muscles, and absent in the submaxillary muscle. (3) In pottasium contractures of muscle strips made from the submaxillary muscle, muscle strips consisting of muscle fibers with low alkaline-stable myosin ATPase and high SDHase activities exhibited a prolonged contraction, while those consisting of muscle fibers with high alkaline-stable myosin ATPase and low SDHase activities exhibited a transient contraction. This indicates that the former muscle strips were composed of tonic muscle fibers and the latter were composed of twitch muscle fibers. Comparison of tetanic contractions between both the muscle strips supported the same conclusion. (4) Variation in the appearance of the reflex discharges enabled a rough division of motoneurons into phasic, intermediate, and tonic types. Some motoneurons could not be classified, however. Based on these results, the mechanism of motor control in tonic jaw reflexes is discussed. 松本歯科大学学会 1989-08-31 jpn journal article VoR https://mdu.repo.nii.ac.jp/records/1148 AN00232590 0385-1613 松本歯学 15 2 150 166 https://mdu.repo.nii.ac.jp/record/1148/files/matsumoto_shigaku_15-02-03.pdf application/pdf 1.7 MB 2012-05-24