1. Laboratory of Physiology I, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa 252-5201, Japan
2. Tsukuba Racehorse Clinic, 2-15-36 Higashi, Tsukuba, Ibaraki 305-0046, Japan
3. Matsunaga Veterinary Clinic, 3334-2 Sakura, Inashiki, Ibaraki 300-0508, Japan
4. Laboratory of Physiology II, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa 252-5201, Japan
5. Laboratory of Anatomy II, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa 252-5201, Japan