Effects of an anesthetic mixture of medetomidine,midazolam, and butorphanol
in rats—strain difference and antagonism by atipamezole |
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Authors: | Yumiko Kirihara Mayumi Takechi Kaoru Kurosaki Yuta Kobayashi Yoji Saito Takashi Takeuchi |
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Abstract: | An anesthetic mixture of medetomidine (MED), midazolam (MID), and butorphanol (BUT) has
been used in laboratory animals. We previously reported that this anesthetic mixture
produced closely similar anesthetic effects in BALB/c and C57BL/6J strains. We also
demonstrated the efficacy of atipamezole (ATI), an antagonist of MED that produced quick
recovery from anesthesia in mice. Anesthetics have various anesthetic effects among animal
strains. However, the differences in the effects of anesthetic mixtures in rats are
unclear. In the present study, we first examined effects of the abovementioned anesthetic
mixture using three different rat strains: Wistar (WST), Sprague-Dawley (SD), and Fischer
344 (F344). Second, we examined how different dosages and optimum injection timing of ATI
affected recovery from anesthesia in rats. We used the anesthetic score to measure
anesthetic duration and a pulse oximeter to monitor vital signs. We found no significant
differences in anesthetic duration among the three different strains. However, recovery
from anesthesia in the SD strain took significantly longer than in the other strains. The
antagonistic effects of ATI (0.15 mg/kg and 0.75 mg/kg) were equivalent when administered
at 30 min after anesthetic mixture administration. The antagonistic effects of ATI 0.75
mg/kg were stronger than those of ATI 0.15 mg/kg at 10 min after anesthetic mixture
administration. This anesthetic mixture is a useful drug that can induce similar
anesthetic effects in three different strains and has an antagonist, ATI, that makes rats
quickly recover from anesthesia. These results may contribute to the welfare of laboratory
animals. |
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Keywords: | anesthetic mixture antagonist pulse oximeter rats strain difference |
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