Original Article

Tetrodotoxin, a toxic substance obtained from the globe fish, has been known to paralise the neuromuscular system as well as the central nervous system and recently, it was found to block production of the action potential through its selective inhibition of the sodium-carrying mechanism, but has no effect on the resting potential. In this paper, the effects of tetrodotoxin on the four kinds of skeletal muscle fibers were compared and analysed. Four muscle fibers are tonic and phasic fibers of the extrafusal muscle, and nuclear-bag and nuclear-chain fibers of the intrafusal muscle fibers. The extrafusal muscle is a dynamic source of posture and locomotion, the intrafusal muscle being the regulating source of them. Paralysis of the extrafusal muscle fibers was determined by measuring the decrease in maximum contraction of the soleus (tonic muscle) and tibialis anterior (phasic) produced stimulation of the distal cut end of the ventral root. Paralysis of the intrafusal muscle fibers wasmeasured by a change in the frequency of Group la discharge led from the functionally isolated single filaments of the distal cut end of the dorsal root. By intravenous administration of 4γ/kg tetrodotoxin, paralysis advaces beginning with the intrafusal muscle fibers, and then on to the tonic muscle and phasic muscle fibers. They recover according to the same order. When the intrafusal muscle fiber recovers during an advance in paralysis of the extrafusal muscle, intrafusal muscle fibers contract by the γ-efferent activated by stimulation of the ventral root, and the Group la discharge increases. Frequency of the Group la discharge increases in proportion to muscle extension, therefore the contraction curve of the intrafusal muscle fiber is measured from augmentation of the discharge frequency. Contraction of the intrafusal muscle fibers lasts for several hundred msec, and the curve has two peaks at about 60 msec, and 110 (Fig. 5).It is clear then that the former corresponds to contraction of the nuclear-bag fiber, and the latter to contraction of the nuclearchain fiber

当科うつ病入院患者における治療経過中の血圧変動

うつ病と高血圧などの心血管系疾患ついては関連を示唆する多くの報告があるが、一定の見解には至っていない。そこで今回我々は、抑うつ症状の悪化を契機に当科に入院した大うつ病性障害患者12名の入院後1週間の平均血圧と症状改善後の安定期の平均血圧を調査・検討した。その結果、全12例の平均では入院時（117/71mmHg）と安定期（114/71mmHg）で血圧に差はなかったが、単一エピソード群（3名：131/78→ 105/67）で反復性群（9名：112/68→ 116/72）と比較して入院時に上昇していた血圧が安定期には低下する傾向が認められた。また、高齢の単一エピソード群には症状の悪化と血圧の上昇が相関している症例も存在した。以上から、高齢の初発例では血圧上昇を起こしやすい可能性も考えられ、診察する際には留意する必要があると思われた

単純超低体温下開心術の術後合并症

Article信州医学雑誌 19(2): 146-151(1971)journal articl