Itoh T, Kuriyama H, Ueno H
J Physiol. 1983 Oct;343:233-52. doi: 10.1113/jphysiol.1983.sp014890.
The effects of nitroglycerine (NG) on the mechanical responses of small pieces of intact and skinned smooth muscles of the mesenteric artery, were investigated, as were the Ca fluxes of isolated smooth muscle cells of the coronary artery. NG (10(-6)-10(-5) M) inhibited both phasic and tonic components of the K-induced contraction; however, the tonic component was more sensitive to NG. The minimum concentration of NG required to decrease significantly the tonic response evoked by 39 mM-external K was 10(-8) M. NG (10(-5) M) reduced the number of oscillatory contractions evoked by 10(-5) M-noradrenaline (NAd). After complete removal of stored Ca, the addition of Ca did not produce contraction in polarized muscle (5.9 mM-external K), yet depolarized muscles (128 mM-external K) did contract. Addition of NG (10(-5) M) with Ca produced no change in the resting tone in polarized muscles but inhibited the contraction in depolarized muscles. After application of NG (10(-5) M), caffeine or NAd consistently produced smaller contraction in both polarized and depolarized muscles in Ca-free solution. NG (10(-5) M) inhibited the Na-free contraction evoked by prolonged treatment with Na-free solution. Contractions evoked by repetitive applications of 10(-5) M-NAd or 10 mM-caffeine persisted longer in Na-free, Ca-free (EGTA) solution than those observed in Ca-free Krebs solution, but when NG was added to the Na-free, Ca-free (EGTA) solution, the contractions ceased more rapidly than in the absence of NG. In chemically skinned muscles, 10(-5) M-NG had no effect on the pCa-tension relationship. The absolute amplitude of Ca-induced contraction was also not affected by 10(-5) M-NG. In these muscles, when the amount of stored Ca was estimated from the amplitude of the caffeine-induced contraction, Ca accumulation into and release from store sites were unaffected by 10(-5) M-NG. The effects of 10(-5) M-NG on the accumulation and efflux of 45Ca in isolated cell suspensions prepared from the porcine coronary artery were investigated. The amount of 45Ca taken up by cells after 1-30 min incubation in 45Ca-containing solution, and the 45Ca efflux in Ca-free (EGTA) solution, were not affected by 10(-5) M-NG. In the presence of 3 X 10(-6) M-acetylcholine (ACh), the efflux of 45Ca into Ca-free (EGTA) solution was accelerated and with the addition of 10(-5) M-NG plus 3 X 10(-6) M-ACh, this efflux was even further enhanced.(ABSTRACT TRUNCATED AT 400 WORDS)
研究了硝酸甘油（NG）对肠系膜动脉完整和去皮小块平滑肌机械反应的影响，以及对冠状动脉分离平滑肌细胞钙通量的影响。NG（10⁻⁶ - 10⁻⁵ M）抑制钾诱导收缩的相性和张力性成分；然而，张力性成分对NG更敏感。显著降低39 mM细胞外钾诱发的张力反应所需的NG最低浓度为10⁻⁸ M。NG（10⁻⁵ M）减少了10⁻⁵ M去甲肾上腺素（NAd）诱发的振荡性收缩次数。完全去除储存钙后，添加钙在极化肌肉（5.9 mM细胞外钾）中不产生收缩，但去极化肌肉（128 mM细胞外钾）会收缩。添加NG（10⁻⁵ M）和钙对极化肌肉的静息张力无影响，但抑制去极化肌肉的收缩。应用NG（10⁻⁵ M）后，咖啡因或NAd在无钙溶液中对极化和去极化肌肉均持续产生较小收缩。NG（10⁻⁵ M）抑制无钠溶液长时间处理诱发的无钠收缩。在无钠、无钙（乙二醇双四乙酸）溶液中，重复应用10⁻⁵ M - NAd或10 mM咖啡因诱发的收缩持续时间比在无钙Krebs溶液中更长，但当向无钠、无钙（乙二醇双四乙酸）溶液中添加NG时，收缩比不添加NG时停止得更快。在化学去皮肌肉中，10⁻⁵ M - NG对pCa - 张力关系无影响。钙诱导收缩的绝对幅度也不受10⁻⁵ M - NG影响。在这些肌肉中，当根据咖啡因诱导收缩的幅度估计储存钙量时，钙向储存位点的积累和从储存位点的释放不受10⁻⁵ M - NG影响。研究了10⁻⁵ M - NG对从猪冠状动脉制备的分离细胞悬液中⁴⁵Ca积累和流出的影响。在含⁴⁵Ca溶液中孵育1 - 30分钟后细胞摄取的⁴⁵Ca量，以及在无钙（乙二醇双四乙酸）溶液中的⁴⁵Ca流出量，均不受10⁻⁵ M - NG影响。在存在3×10⁻⁶ M乙酰胆碱（ACh）的情况下，⁴⁵Ca向无钙（乙二醇双四乙酸）溶液中的流出加速，添加10⁻⁵ M - NG加3×10⁻⁶ M - ACh时，这种流出进一步增强。（摘要截于400字）
