マウス運動神経末端における伝達物質遊離に対する塩化第一スズおよび塩化第二スズの作用

Stannous chloride (SnCl_2) is thought to facilitate the transmitter release from the motor nerve terminals. Stannous ions tend to become oxidized to stannic ions (Sn^) in the presence of water and oxygen. Therefore, the results seen with SnCl_2 until now might reflect the properties of Sn^. In the present study, to ascertain whether SnCl_2 facilitates the transmitter release from mouse motor nerve terminals, we compared the effects of stannic chloride (SnCl_4) on the miniature endplate potential (m. e. p. p.) frequency and the quantal content of the endplate potential (e. p. p.) with those of SnCl_2. We statistically analyzed the mean values of the differences of SnCl_2 (30μM) from its control and of SnCl_4 (30μM) from its control. There were significant differences between the two, both in the m. e. p. p. frequency and in the quantal content. The results obtained demonstrate that the actions of Sn^ are not involved in the effects shown by SnCl_2. We conclude that SnCl_2 facilitates the transmitter release from mouse motor nerve terminals

Label-Free Electrical Detection Using Carbon Nanotube-Based Biosensors

Label-free detections of biomolecules have attracted great attention in a lot of life science fields such as genomics, clinical diagnosis and practical pharmacy. In this article, we reviewed amperometric and potentiometric biosensors based on carbon nanotubes (CNTs). In amperometric detections, CNT-modified electrodes were used as working electrodes to significantly enhance electroactive surface area. In contrast, the potentiometric biosensors were based on aptamer-modified CNT field-effect transistors (CNTFETs). Since aptamers are artificial oligonucleotides and thus are smaller than the Debye length, proteins can be detected with high sensitivity. In this review, we discussed on the technology, characteristics and developments for commercialization in label-free CNT-based biosensors

ラット神経筋伝達に対する塩化第一スズの作用

Stannous chloride (SnCl_2) facilitates frog neuromuscular transmission. Effects of SnCl_2 on the neuromuscular junction of the rat have been investigated to determine whether mammalian responses to SnCl_2 are the same as those of amphibians. SnCl_2 (30 μM) had no effect on the resting potential or the membrane resistance of the muscle fiber. SnCl_2 did not change the amplitude of the endplate potential. SnCl_2 significantly raised the frequency of the miniature endplate potential in the high potassium-medium. SnCl_2 decreased the amplitude of the miniature endplate potential. These results suggest that SnCl_2 may facilitate the transmitter release from the nerve terminals, but it may reduce the acetylcholine sensitivity of the endplate in the rat

有害金属拮抗薬DMSAおよびDMPSのヒ酸ナトリウムの排泄に対する作用

Previous studies have shown that DMSA (meso-2, 3-dimercaptosuccinic acid, succimer) and DMPS (2, 3-dimercapto-1-propane sulfonic acid, Na salt, unithiol) are effective antidotes for pentavalent arsenate and trivalent arsenite because they reduce the mortality of mice poisoned with these arsenic compounds. Studies have also shown that in mice treated with arsenite, DMPS and DMSA promote excretion of arsenic into the bile and urine, respectively. This study was conducted to determine whether DMSA and DMPS promote arsenate excretion to the same extent as previously reported for arsenite. The results demon-strated that DMPS antagonized arsenate toxicity by improving excretion of arsenic, although to a lesser extent than in studies with arsenite, while DMSA showed a slight but statistically insignificant promotion of early arsenic excretion in the urine

Scores of Fatigue Complaints in High School Students in Physical Education Classes

This study was undertaken to give scientific basis in introducing exercise into our daily lives. Fatigue scores, the Flicker value, the counter value, grip strength and counting steps were analyzed in 109 female high school students before and after physical education classes during the third school period. These female students were chosen because of their lower fatigue scores, particularly before lunch time. Fatigue scores were obtained in tumbling exercises, softball, badminton, team handball, basketball and a 2.2-km distance run during 50-min classes. Step-counting activities were the lowest in tumbling with 640 steps, and the highest in the 2.2-km distance run with 2,580 steps. In all activities except the distance run, fatigue scores decreased, and the Flicker value and the counter value increased after exercise. Grip strength decreased only in softball and the distance run. In the distance run, all measurements of the tests showed tendencies toward fatigue. However, with lighter exercises, the fatigue scores decreased by 1,760 steps; also, the Flicker value and the counter value showed improvement of physical function. Therefore, it is suggested that exercise having around 1,760 steps, corresponding to approximately 35 steps/min, might be the upper limit of physical load at which fatigue symptoms increase in a physical education class. Physical activities in the physical education classes showed two types of effects: recreational effects and training effects

塩化第一スズのカエル心筋攣縮に対する作用

Stannous chloride (SnCl_2) increases the calcium (Ca) entry into motor nerve terminals. Three kinds of Ca channels have been found in nerves (i.e., L-, N-, and T-types). To determine whether or not L-type Ca channels participate in the SnCl_2-induced increase in Ca entry, the effect of SnCl_2 on the twitch of the bullfrog auricular muscle was investigated and compared with that of the modulator selective to each type of the Ca channels. Both nifedipine (20μM) and nicardipine (20μM), L-type Ca channel blockers, inhibited the twitch. Although Bay K 8644 (20μM), a Ca agonist of the L-type Ca channels, augmented the twitch, SnCl_2 (0.1mM) did not. NiCl_2 (0.1mM), a T-type Ca channel blocker, had no effect on the twitch. The results obtained suggest that SnCl_2 may not activate the L-type Ca channels and that SnCl_2 might be likely to enhance the Ca entry into the motor nerve terminals by activating the N-type channels

塩化第二スズによるマウス神経筋伝達の抑制

The present study was conducted to determine whether stannic chloride (SnCl_4) at concentrations above 50цM inhibits or facilitates neuromuscular transmission. SnCl_4 decreased the amplitude of the endplate potential (e.p.p.) concentration-dependently in a concentration range from 0.05 to 0.5mM. Not only SnCl_4 (0.5mM) but also tartaric acid (TA, 0.5mM), a solvent for 0.5 mM SnCl_4, decreased the e.p.p.. The action of SnCl_4 was stronger than that of TA. Both SnCl_4 (0.5mM) and TA (0.5mM) decreased the quantal content of the e.p.p., and the action of the former was significantly stronger than that of the latter. SnCl_4 (0.5mM) raised the frequency of the miniature endplate potential (m.e.p.p.), whereas TA (0.5mM) reduced it. SnCl_4 (0.5mM) decreased the m.e.p.p. amplitude as did TA (0.5mM). The results obtained show that SnCl_4 inhibits neuromuscular transmission by decreasing the volume of the transmitters released by nerve impulses