Diaphragm muscle fibers

Holmes and Robins reported that 2-PAM I overcame neuromuscular blockade induced by DFP, TEPP, or sarin, but this could be demonstrated with the Isolated phrenic nerve-diaphragm preparation from the rat only after washing away excess OP compound. Intravenous injection of 2-PAM I overcame slowly neuromuscular blockade induced by OP compounds. The oxime, they found, also had a direct toxic action on muscle, reducing the ability of muscle to shorten and decreasing the ability of muscle fibers to conduct impulses. The same investigators reported that V (intraperltoneally at 150 mg/kg) had little, if any, effect on a sarin-induced blockade of neuromuscular transmission. 

Laskowski et al (1975) reported the ultrastructural changes in the subsynaptic folds that were quite varied even between muscle fibers from the same diaphragm of rats acutely treated with paraoxon. The fact that some endplates were totally degenerated after 2 days of paraoxon treatment... 

In recent years, much attention has been paid to the role of calcium in receptor phenomena, besides its better known involvement in enzyme activation and contraction of muscle fibers. Earlier observations by Csillik and Savay (30) and Nakamura et al. (31) led Tazieff-Depierre and co-workers (32) to study calcium release at the motor end plates of mouse diaphragm in relation to receptor activation and inhibition. Of considerable interest was the observation that whereas membrane de-... 

TABLE 1. Prevention of DFP-induced Increase in TBA-MDA and Muscle Fiber Necrosis in Rat Diaphragm by d-Tubocurarine and U-78517F ... 

Hypothyroidism may result in motor unit type-specific adaptations in NMJ structure. Using confocal microscopy to analyze the effect of hypothyroidism on the three-dimensional structure of NMJs in the rat diaphragm muscle, Prakash et al. (1996a) found that hypothyroidism reduced the planar area of both axon terminals and motor end-plates at type 1 and Ila muscle fibers, and decreased the number of branches and mean branch length. In contrast, morphological adaptations were not evident for... 

Effect of Hypothyroidism on Velocity of Shortening In isolated fibers from hypothyroid muscles, is dramatically slowed across fiber types. Hypothyroidism results in a slower for the rat diaphragm muscle (Figure 111.6a) (Gosselin et al., 1996 Herb et al., 1996) and hind-limb muscles (Caiozzo... 

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