Antispastic Effect of Fasudil and Cocktail of Fasudil and Nitroglycerin in Internal Thoracic Artery

Background Spasm of arterial grafts in coronary artery bypass grafting is a clinical problem and can occasionally be lethal. Perioperative spasm in the internal thoracic artery (ITA) and coronary arteries occurs in 0.43% of patients. This study aimed to investigate the antispastic effect of a RhoA/Rho-kinase (Rho-associated coiled-coil-containing protein kinase [ROCK]) inhibitor (fasudil) with and without nitroglycerin in combination in the ITA. Methods Isolated human ITA rings taken from 68 patients who were undergoing coronary bypass were studied in a myograph. Cumulative concentration-relaxation curves for fasudil (−9 to −3.5 log M) were established in the ITA, which was precontracted with potassium chloride or U46619. The inhibitory effect of fasudil (−6.3 or −5.3 log M) or fasudil in combination with nitroglycerin were also tested. The ROCK2 protein was measured by Western blot. Results Fasudil caused similar relaxation in ITA rings contracted by potassium chloride or U46619. Pretreatment with −5.3 log M fasudil significantly depressed contraction induced by potassium chloride (P = .004 vs control; P = .017 vs −6.3 log M) and U46619 (P = .010 vs control; P = .041 vs. −6.3 log M). Fasudil in combination with nitroglycerin had more effect and more rapid and sustained relaxation than either vasodilator alone. Fasudil caused a decrease of ROCK2 protein content (P = .014). Conclusions Fasudil fully relaxes some vasoconstrictor-induced contraction and decreases ROCK2 protein content in the ITA. The combination of fasudil and nitroglycerin has a superior effect than either vasodilator alone. The new cocktail solution composed of fasudil and nitroglycerin (pH 7.4) has effective antispastic action and may prove to be a new antispastic method for arterial conduits during coronary bypass surgery.