H 2 Mediates Cardioprotection Via Involvements of K ATP Channels and Permeability Transition Pores of Mitochondria in Dogs Akemi Yoshida & Hiroshi Asanuma & Hideyuki Sasaki & Shoji Sanada & Satoru Yamazaki & Yoshihiro Asano & Yoshiro Shinozaki & Hidezo Mori & Akito Shimouchi & Motoaki Sano & Masanori Asakura & Tetsuo Minamino & Seiji Takashima & Masaru Sugimachi & Naoki Mochizuki & Masafumi Kitakaze Published online: 17 April 2012 # Springer Science+Business Media, LLC 2012 Abstract Purpose Inhalation of hydrogen (H 2 ) gas has been shown to limit infarct size following ischemia-reperfusion injury in rat hearts. However, H 2 gas-induced cardioprotection has not been tested in large animals and the precise cellular mech- anism of protection has not been elucidated. We investigated whether opening of mitochondrial ATP-sensitive K+ chan- nels (mK ATP ) and subsequent inhibition of mitochondrial permeability transition pores (mPTP) mediates the infarct size-limiting effect of H 2 gas in canine hearts. Methods The left anterior descending coronary artery of beagle dogs was occluded for 90 min followed by reperfusion for 6 h. Either 1.3% H 2 or control gas was inhaled from 10 min prior to start of reperfusion until 1 h of reperfusion, in the presence or absence of either 5-hydroxydecanoate (5-HD; a selective mK ATP blocker), or atractyloside (Atr; a mPTP opener). Results Systemic hemodynamic parameters did not differ among the groups. Nevertheless, H 2 gas inhalation reduced infarct size normalized by risk area (20.6±2.8% vs. control gas 44.0±2.0%; p <0.001), and administration of either 5- HD or Atr abolished the infarct size-limiting effect of H 2 gas (42.0±2.2% with 5-HD and 45.1±2.7% with Atr; both p <0.001 vs. H 2 group). Neither Atr nor 5-HD affected infarct size per se. Among all groups, NAD content and the number of apoptotic and 8-OHdG positive cells was not significantly different, indicating that the cardioprotection A. Yoshida : H. Sasaki : S. Yamazaki : M. Asakura : M. Kitakaze (*) Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita 565-8565, Osaka, Japan e-mail: kitakaze@zf6.so-net.ne.jp H. Asanuma Department of Cardiovascular Science and Technology, Kyoto Prefectural University of Medicine, Suita 565-8565, Osaka, Japan A. Yoshida : N. Mochizuki Department of Structural Analysis, National Cerebral and Cardiovascular Research Center, Suita, Japan S. Sanada : Y. Asano : T. Minamino : S. Takashima Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan Y. Shinozaki : H. Mori Department of Physiological Science, Tokai University Graduate School of Medicine, Isehara, Japan A. Shimouchi Department of Cardiac Physiology, National Cerebral and Cardiovascular Research Center, Suita, Japan M. Sano Department of Cardiology, Keio University School of Medicine, Tokyo, Japan M. Sugimachi Department of Cardiovascular Dynamics, Research Institute, National Cerebral and Cardiovascular Center, Suita, Japan Cardiovasc Drugs Ther (2012) 26:217–226 DOI 10.1007/s10557-012-6381-5