CELLULAR BIOLOGY OF ANTIANGINAL AGENTS ; DEVELOPMENT AND EVALUATION OF NEW DRUGS.

本研究的目的是（i）阐明各种血管平滑肌的信号转导机制，（ii）确定已知的抗心绞痛药物对信号转导的影响，（iii）开发新的抗心绞痛药物。(1)采用前表面荧光法和Fura-2-负载的猪冠状动脉条，同时测量硝酸甘油（NG）对细胞内Ca浓度（Ca）i和张力发展的影响。NG积极降低（Ca）i和张力，无论是在休息或刺激下的高K去极化或组胺条。对于NG诱导的松弛，张力降低的程度大于根据K去极化观察到的（Ca）i-张力关系从（Ca）i降低所预期的程度。在细胞外钙的情况下，NG耗尽存储的钙，也抑制释放的钙从组胺敏感的商店。因此，NG通过降低（Ca）i来松弛猪的冠状动脉。此外，独立的（Ca）i的变化，第二信使，积极的环GMP，可能直接影响的收缩元素在NG诱导的放松。(2)钙拮抗剂地尔硫卓在浓度低于10 μ M时，可抑制细胞外Ca依赖性的（Ca）i增加（Ca内流通过Ca通道），并引起与（Ca）i减少成正比的张力发展的降低，但对收缩元件的Ca敏感性无影响。在高浓度，0.1 mM，地尔硫卓抑制钙释放从细胞内存储网站，possively通过抑制受体网站的激动剂的结合。(3)发现一种新合成的磷酸二酯酶抑制剂可通过ATP敏感性钾通道开放介导的机制抑制钙内流，并可从内皮细胞释放舒张因子。

The purposes of this study are to (i) clarify the mechanisms of signal transductions in various vascular smooth muscle, (ii) determine the effect of well known antianginal agents on the signal transduction, and (iii) develop new antianginal drugs. (1) Using front-surface fluorometry and fura-2-loaded strips of the coronary artery of the pig, the effect of nitroglycerin (NG) on cytosolic Ca concentration, (Ca)i, and on tension development were measured simultaneously. NG actively reduced both (Ca)i and tension, irrespective of whether strips were at rest or under stimulation with either high-K-depolarization or histamine. For NG-induced relaxation, the extent of the decrease in tension was greater than that expected from the reduction of (Ca)i based on the (Ca)i-tension relation observed with K-depolarization. In the absence of extracellular Ca, NG depleted stored Ca and also inhibited the release of Ca from histamine-sensitive stores. Thus, NG relaxes the coronary artery of the pig by reducing (Ca)i. In addition, and independent of the (Ca)i change, a second messenger, positively cyclic GMP, may directly influence the contractile elements during NG-induced relaxation. (2) Diltiazem, a Ca-antagonist, in a concentration lower than 10 uM, inhibited extracellular Ca-dependent increases in (Ca)i (Ca influx through Ca channels), and secondarily caused decreases in tension development which was proportional to (Ca)i decrease, with no effect on Ca-sensitivity of the contractile elements. At high concentration, 0.1 mM, diltiazem inhibited Ca-release from intracellular store sites, possively by inhibiting binding of the agonist at receptor sites. (3) It was found that a newly synthetized inhibitor of phosphodiesterase could inhibit Ca-influx through mechanisms mediated by opening of the ATP-sensitive K channels, and also could release relaxing factor from endothelial cells.