Nicardipine co-administered with medetomidine-midazolam-butorphanol anesthesia attenuates post-anesthetic hypothermia in rats.

Medetomidine-midazolam-butorphanol (MMB) anesthesia is widely used in laboratory rodents but is frequently accompanied by peri- and post-anesthetic hypothermia. This study examined whether co-administration of nicardipine could attenuate hypothermia associated with MMB anesthesia in rats, thereby testing the concept that modulation of peripheral vascular tone can complement thermal management. Rats received MMB alone (0Ni) or MMB combined with nicardipine at 0.25 or 0.5 mg/kg. Body temperature was assessed under warmed and non-warmed conditions, and systolic blood pressure (SBP) and heart rate (HR) were monitored to evaluate cardiovascular effects. Under warmed conditions, body temperature profiles did not differ among groups. Under non-warmed conditions, however, nicardipine-treated rats maintained higher body temperatures during recovery, and both nicardipine groups showed significantly higher recovery-phase AUC values than the 0Ni group. Nicardipine did not significantly alter induction or recovery timing. In parallel, nicardipine produced a dose-dependent reduction in SBP and an increase in HR, particularly at 0.5 mg/kg. These findings suggest that nicardipine partially attenuates post-anesthetic hypothermia during recovery from MMB anesthesia under non-warmed conditions and may serve as a complementary approach to thermal management. However, the marked SBP reduction observed at 0.5 mg/kg warrants caution in practical application.