Beneficial effect of hydroxyfasudil, a specific Rho-kinase inhibitor, on ischemia/reperfusion injury in canine coronary microcirculation in vivo
Toyotaka Yada, MD, PhD*,*,
Hiroaki Shimokawa, MD, PhD ,
Osamu Hiramatsu, PhD*,
Tatsuya Kajita, MD, PhD*,
Fumiyuki Shigeto, MD, PhD*,
Etsuro Tanaka, MD, PhD ,
Yoshiro Shinozaki, BS ,
Hidezo Mori, MD, PhD||,
Takahiko Kiyooka, MD#,
Masashi Katsura, PhD¶,
Seitaro Ohkuma, MD, PhD¶,
Masami Goto, MD, PhD*,
Yasuo Ogasawara, PhD* and
Fumihiko Kajiya, MD, PhD#
* Department of Medical Engineering and Systems Cardiology, Kawasaki Medical School, Kurashiki, Japan
Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
Department of Physiology, Tokai University School of Medicine, Isehara, Japan
|| Department of Cardiac Physiology, National Cardiovascular Center Research Institute, Suita, Japan
¶ Department of Pharmacology, Kawasaki Medical School, Kurashiki, Japan
# Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
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Figure 1 Experimental protocol. S = serotonin; L = L-NMMA; HF = hydroxyfasudil; Ach = acetylcholine; P = papaverine; Occl = coronary occlusion.
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Figure 2 Coronary vasodilator effects of hydroxyfasudil in dogs in vivo. Hydroxyfasudil (10, 30, and 100 µg/kg, IC) caused coronary vasodilation, in a dose-dependent manner, under normal conditions in both small arteries (a) and arterioles (b). Number of vessels per animal used was 5/3 in small arteries and 7/4 in arterioles, respectively. Hydroxyfasudil also increased coronary blood flow (CBF) in a dose-dependent manner (c). *p < 0.05.
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Figure 3 Effects of hydroxyfasudil on serotonin-induced coronary vascular responses in dogs in vivo. Hydroxyfasudil converted the serotonin-induced vasoconstriction of small arteries to vasodilation (a) and significantly enhanced the serotonin-induced vasodilation of arterioles (b). L-NMMA significantly attenuated the serotonin-induced vasodilation, which was counteracted by hydroxyfasudil. Number of vessels per animal used was 18/6 for S, L + S and HF + S, 13/4 for L + HF + S. *p < 0.05, **p < 0.01. S = serotonin; L = L-NMMA; HF = hydroxyfasudil; B = before drug; A = after drug.
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Figure 4 Endothelium-dependent coronary vasodilation before and after coronary ischemia/reperfusion (I/R) injury in dogs in vivo. Coronary I/R significantly impaired coronary vasodilation to acetylcholine under control conditions (C) and L-NMMA (L) further suppressed the vasodilation, whereas hydroxyfasudil (HF) completely preserved the responses. The vasoconstriction induced by L-NMMA after I/R was significantly improved by hydroxyfasudil in small arteries. Hydroxyfasudil also prevented the decrease in coronary blood flow (CBF) after I/R, which effect was attenuated by L-NMMA. Number of vessels per animals used was 7/6 for control (mean diameter 120 ± 7 µm), 5/4 for L-NMMA (123 ± 8 µm), 6/4 for hydroxyfasudil (118 ± 8 µm), and 5/4 for hydroxyfasudil plus L-NMMA (125 ± 9 µm) in small arteries, and 12/6 for control (70 ± 6 µm), 8/4 for L-NMMA (69 ± 7 µm), 8/5 for hydroxyfasudil (68 ± 7 µm), and 11/6 for hydroxyfasudil plus L-NMMA (71 ± 5 µm) in arterioles. I/R = ischemia/reperfusion; B = before acetylcholine; A = after acetylcholine. *p < 0.05; **p < 0.01.
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Figure 5 Coronary microvascular responses to acetylcholine before and after coronary ischemia/reperfusion (I/R) injury in dogs in vivo. Under control conditions, I/R significantly impaired coronary vasodilator response to acetylcholine (a), whereas hydroxyfasudil completely preserved the responses in the absence (c) or presence of L-NMMA (d) compared with that in the presence of L-NMMA alone (b). Number of vessels per animals used was 19/7 under control conditions (before I/R: y = –0.3x + 35.9, r = 0.85; after I/R: y = –0.2x + 18.1, r = 0.80), 13/4 for L-NMMA alone (before I/R: y = –0.2x + 35.1, r = 0.76; after I/R: y = –0.2x + 12.2, r = 0.88), 14/7 for hydroxyfasudil (before I/R: y = –0.2x + 27.9, r = 0.73; after I/R: y = –0.2x + 27.4, r = 0.80), and 16/7 for hydroxyfasudil plus L-NMMA (before I/R: y = –0.2x + 31.8, r = 0.83; after I/R: y = –0.2x + 19.2, r = 0.86). **p < 0.01. Open circles = before I/R; solid circles = after I/R.
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Figure 6 Endothelium-independent coronary vasodilation before and after coronary I/R injury in dogs in vivo. Coronary vasodilator response to papaverine was comparable under all conditions in both small arteries and arterioles. Number of vessels per animals used was 7/6 for control (mean diameter 120 ± 7 µm), 5/4 for L-NMMA (123 ± 8 µm), 6/4 for hydroxyfasudil (118 ± 8 µm), and 5/4 for hydroxyfasudil plus L-NMMA (125 ± 9 µm) in small arteries; and 12/6 for control (70 ± 6 µm), 8/4 for L-NMMA (69 ± 7 µm), 8/5 for hydroxyfasudil (68 ± 7 µm), and 11/6 for hydroxyfasudil plus L-NMMA (71 ± 5 µm) in arterioles. C = control; L = L-NMMA; HF = hydroxyfasudil. I/R = ischemia/reperfusion. B = before papaverine; A = after papaverine.
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Figure 7 Western blotting showing the effects of hydroxyfasudil (HF) on Rho-kinase activity and on eNOS protein expression in the myocardium of LAD and LCX. (a) Rho-kinase activity in coronary artery; (b) expression of eNOS protein in endocardium; (c) expression of eNOS protein in epicardium. Rho-kinase activity was determined by the degree of ezrin-radixin-moesin phosphorylation (p-ERM/t-ERM). Rho-kinase activation in the ischemic LAD was completely inhibited by cotreatment with hydroxyfasudil. Expression of eNOS protein in the ischemic endocardium of LAD area was significantly decreased compared with the non-ischemic endocardium of LCX area, which was again improved by hydroxyfasudil. *p < 0.05, **p < 0.01.
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Figure 8 (a) Ischemia/reperfusion (I/R)-induced LV infarct size in dogs in vivo. Hydroxyfasudil significantly reduced the I/R-induced LV infarct size. The beneficial effect of hydroxyfasudil was partially attenuated by L-NMMA, while L-NMMA alone did not significantly increase the infarct size. Number of animals used was each 7 for C, HF, and L + HF, and 4 for L. C = control; L = L-NMMA; HF = hydroxyfasudil. **p < 0.01. (b) Plot of infarct size expressed as a percentage of the risk area and regional collateral flow during ischemia. In the control group, there was an inverse relation between infarct area and collateral flow measured by microsphere (r = 0.93, p < 0.01), and hydroxyfasudil significantly shifted the regression line downward as compared with the control group (p < 0.01). Number of animals used was five for control conditions and four for hydroxyfasudil.
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