Biol. Pharm. Bull. 30(9) 1716—1720 (2007)

the viewpoint of not only animal welfare but also the reliability of pharmacological studies. The type of anesthetics used may vary depending on the type of experiment required or the study design. Some anesthetics have cardioor renoprotective effects, which may be relevant in designing ischemiareperfusion protocols. Several studies have examined the influence of commonly used anesthetics on the short-term and noninvasive assessment of cardiac function via echocardiography. Zuurbier et al. reported that at similar surgical levels of anesthesia, the preferred anesthetic (isoflurane or ketamine–medetomidine–atropine) depends on the mouse strain used and whether monitoring of the blood pressure or heart rate is the focus of the study. Sodium pentobarbital and ketamine/xylazine have been widely used as anesthetics in mice. However, Chaves et al. reported that inhalation anesthetic agents such as halothane have significant advantages when compared with injectable agents such as ketamine/xylazine. It has been reported that when compared with other injectable anesthetics, such as pentobarbital and ketamine/xylazine, isoflurane anesthesia has a slight effect on the hemodynamic status of mice. Therefore, in animal experiments, it is important to consider the option of inhalation anesthesia. Indeed, the methodology of administering anesthesia changed markedly between the periods from 1990 to 1992 and from 2000 to 2002. Notably, there was an increase in the use of isoflurane and of injectable anesthetic combinations such as ketamine/ xylazine. However, since ketamine was classified as a narcotic drug in 2006, its use now poses difficulties in Japan. Additionally, since no appropriate instrument for the inhalation anesthesia of mice was available, this technique was performed only in a limited number of laboratories. Thus, the development of a system that can perform the inhalation anesthesia easily was desired. KNI-472, a newly developed anesthetic system that incorporates a ventilator, is the first anesthetic system designed specifically for mice and rats (Fig. 1). We performed inhalation anesthesia with isoflurane using KNI-472 and observed that the hemodynamic parameters in mice were stable. We believe that this stability using KNI-472 was the result of maintaining a constant depth of anesthesia by strictly controlling the concentration of the anesthetic. Therefore, inhalation anesthesia using KNI-472 is an important candidate for a method of general anesthesia. However, there are no results available with which to compare the inhalation anesthesia using KNI-472 with the other widely used anesthesia methods. In this study, we evaluated the difference between the hemodynamic parameters obtained after administering the widely used intraperitoneal pentobarbital anesthesia with those obtained after administering inhalation anesthesia with isoflurane using KNI-472. We believe that the data obtained in this study could provide a basis for anesthetic regimens in future pharmacological studies.