Isoflurane and Sevoflurane Produce a Dose-Dependent Reduction in the Shivering Threshold in Rabbits

Hanagata, Kazuyuki; Matsukawa, Takashi; Sessler, Daniel I.; Miyaji, Takaharu; Funayama, Tadahisa; Koshimizu, Masanobu; Kashimoto, Satoshi; Kumazawa, Teruo

doi:10.1213/00000539-199509000-00028

Cited by 2 publications

(4 citation statements)

References 24 publications

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“…However, unlike the earlier report, in the present study hypothermia occurred in the absence of anesthesia, a state known to induce hypothermia through inhibition of thermoregulatory mechanisms (13,28,30). Our observed heat stress-induced hypothermic response could be interpreted either as an unregulated event due to direct thermal damage to homeostatic sites (e.g., central nervous system) or an adaptive thermoregulatory survival mechanism.…”

Section: Discussioncontrasting

confidence: 85%

“…In rodents, the behavioral spreading of saliva on the ventral body surfaces is an essential mechanism for evaporative heat loss that is prevented under restrained conditions. Anesthesia induces hypothermia through the inhibition of several thermoregulatory mechanisms (13,28,30), thus making the study of T c inappropriate under these conditions. The insertion of rectal probes or attachment of thermocouples induces T c changes, which are difficult to distinguish from hyperthermia in response to an environmental heat load.…”

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confidence: 99%

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Heat stress induces a biphasic thermoregulatory response in mice

Leon

DuBose

Mason

2005

American Journal of Physiology-Regulatory, Integrative and Comp

129

185

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Previous animal models of heat stress have been compromised by methodologies, such as restraint and anesthesia, that have confounded our understanding of the core temperature (T(c)) responses elicited by heat stress. Using biotelemetry, we developed a heat stress model to examine T(c) responses in conscious, unrestrained C57BL/6J male mice. Before heat stress, mice were acclimated for >4 wk to an ambient temperature (T(a)) of 25 degrees C. Mice were exposed to T(a) of 39.5 +/- 0.2 degrees C, in the absence of food and water, until they reached maximum T(c) of 42.4 (n = 11), 42.7 (n = 12), or 43.0 degrees C (n = 11), defined as mild, moderate, and extreme heat stress, respectively. Heat stress induced an approximately 13% body weight loss that did not differ by final group T(c); however, survival rate was affected by final T(c) (100% at 42.4 degrees C, 92% at 42.7 degrees C, and 46% at 43 degrees C). Hypothermia (T(c) < 34.5 degrees C) developed after heat stress, with the depth and duration of hypothermia significantly enhanced in the moderate and extreme compared with the mild group. Regardless of heat stress severity, every mouse that transitioned out of hypothermia (survivors only) developed a virtually identical elevation in T(c) the next day, but not night, compared with nonheated controls. To test the effect of the recovery T(a), a group of mice (n = 5) were acclimated for >4 wk and recovered at T(a) of 30 degrees C after moderate heat stress. Recovery at 30 degrees C resulted in 0% survival within approximately 2 h after cessation of heat stress. Using biotelemetry to monitor T(c) in the unrestrained mouse, we show that recovery from acute heat stress is associated with prolonged hypothermia followed by an elevation in daytime T(c) that is dependent on T(a). These thermoregulatory responses to heat stress are key biomarkers that may provide insight into heat stroke pathophysiology.

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Section: Discussioncontrasting

confidence: 85%

mentioning

confidence: 99%

Heat stress induces a biphasic thermoregulatory response in mice

Leon

DuBose

Mason

2005

American Journal of Physiology-Regulatory, Integrative and Comp

129

185

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“…We chose isoflurane as the treatment based on the rapid induction and recovery time using this anesthetic. Anesthesia is known to blunt thermoregulatory control through a variety of mechanisms (9,18,21). We cannot discount the possibility that mice were hypothermic after anesthesia exposure such that shivering was required for return of T c to baseline levels.…”

Section: Discussionmentioning

confidence: 97%

“…Changes in T c , MA, heart rate, and blood pressure are well-characterized responses to stress (10,22) that may be eliminated with telemetry. Anesthesia induces hypothermia through the inhibition of several thermoregulatory mechanisms, thus making the study of T c difficult under these conditions (9,18,21).…”

mentioning

confidence: 99%

Biotelemetry transmitter implantation in rodents: impact on growth and circadian rhythms

Leon

Walker

DuBose

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

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The implantation of a biotelemetry transmitter for core body temperature (T(c)) and motor activity (MA) measurements is hypothesized to have effects on growth and circadian rhythmicity depending on animal body-to-transmitter (B:T) size ratio. This study examined the impact of transmitter implantation (TM) on body weight, food intake (FI), water intake (WI), and circadian T(c) and MA rhythms in mice (23.8 +/- 0.04 g) and rats (311.5 +/- 5.1 g) receiving no treatment (NT), anesthesia, laparotomy (LAP), and TM. The B:T size ratio was 6:1 and 84:1 for mice and rats, respectively. In mice, body weight required 14 days to recover to presurgical levels and never attained the level of the other groups. FI recovered in 3 days, whereas WI never reached presurgical levels. Rat body weight did not decrease below presurgical levels. FI and WI recovered to presurgical levels in rats by day 2 postsurgery. Anesthesia decreased mouse body weight for 1 wk, but was without effect in rats. LAP significantly decreased body weight for 5 days in mice and 1 day in rats, showing a significant effect of the surgical procedure in the absence of TM in both species. Circadian T(c) and MA rhythms were evident within the first week in both species, indicating dissociation between circadian rhythmicity and recovery of growth variables. Cosinor analysis showed a TM effect on T(c) min, T(c) max, mesor, amplitude, and period of mice, whereas only the amplitude of the rhythm was affected in rats. These data indicate that a large B:T size ratio is associated with minimization of the adverse effects of surgical implantation. We recommend that B:T size ratio, recovery of presurgical body weight, and display of a robust circadian T(c) and MA rhythm be established before collection of biotelemetry data collection under an experimental paradigm.

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Isoflurane and Sevoflurane Produce a Dose-Dependent Reduction in the Shivering Threshold in Rabbits

Cited by 2 publications

References 24 publications

Heat stress induces a biphasic thermoregulatory response in mice

Heat stress induces a biphasic thermoregulatory response in mice

Biotelemetry transmitter implantation in rodents: impact on growth and circadian rhythms

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