Effects of Oral Single-Dose Administration of Sarpogrelate Hydrochloride on Saturation O 2 of Calf Muscle During Plantar Flexion Exercise Masahiro Horiuchi, Koichi Okita, Shingo Takada, Masashi Omokawa, Tadashi Suga, Noriteru Morita, Kagami Hirabayashi, Takashi Yokota, Shintaro Kinugawa, and Hiroyuki Tsutsui Abstract To investigate the effects of a 100-mg oral single-dose administration of sarpogrelate hydrochloride (SH) on saturation O 2 (StO 2 ) of calf muscle in healthy subjects experiencing simulated peripheral arterial disease (0.6 ankle brachial pressure index). Ten subjects performed three kinds of plantar flexion exercises at a work rate of 50% of maximal volunteer contraction for 4 min by using cuff occlusion ischemia,. Subjects performed a control test (C) without ischemia and SH, an ischemia test (I) without SH, and an I + SH test with ischemia. StO 2 , blood pressures (BP), and heart rate (HR) were measured through all experiments. At the end of the exercise, the decrease in StO 2 from baseline in the C and I + SH tests was significantly less than that in the I test (p < 0.05, respectively). However, there were no significant differences in mean BP or HR in any of the exercise conditions. These results indicated that an oral single-dose administration of SH might improve peripheral circulation inde- pendent of any changes in BP and HR. 1 Introduction Sarpogrelate hydrochloride is an effective therapeutic drug that has been widely used for peripheral arterial disease (PAD) patients in Japan [6]. Although it has been reported that long-term oral administration of sarpogrlate hydrochloride improves vascular function in PAD patients [8], investigation of the effects of a single-dose administration of sarpogrelate hydrochloride on PAD patients has been insufficient. Knowledge of these effects is important for the noninvasive, continuous, and accurate evaluation of PAD patients. Saturation O 2 of muscle oxygenation (StO 2 ) derived by near-infrared spec- troscopy (NIRS) is represented by the ratio of HbO 2 to total Hb. It is thought M. Horiuchi (*) Department of Human Care Studies, Hokkaido University of Education, Sapporo, Japan e-mail: horiuchi@hokusho-u.ac.jp E. Takahashi, D.F. Bruley (eds.), Oxygen Transport to Tissue XXXI, Advances in Experimental Medicine and Biology 662, DOI 10.1007/978-1-4419-1241-1_77, Ó Springer ScienceþBusiness Media, LLC 2010 531