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ARS Home » Midwest Area » West Lafayette, Indiana » Livestock Behavior Research » Research » Publications at this Location » Publication #319646
Title: Rapid cooling after acute hyperthermia alters intestinal tissue morphology and increases the systemic inflammatory response in pigs

Author
item JOHNSON, JAY - Purdue University
item SAPKOTA, AVI - Purdue University
item Lay Jr, Donald

Submitted to: Journal of Applied Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2016
Publication Date: 2/18/2016
Citation: Johnson, J., Sapkota, A., Lay Jr., D.C. 2016. Rapid cooling after acute hyperthermia alters intestinal tissue morphology and increases the systemic inflammatory response in pigs. Journal of Applied Physiology. doi: 10.1152/japplphysiol.00685.2015.

Interpretive Summary: Although rapid cooling is regarded as the most effective heatstroke therapy, human deaths still occur due to a systemic inflammatory response that occurs following thermal injury. Unfortunately, our knowledge of the thermal and pathophysiological effects of heatstroke and cooling procedures are often limited to rodent models and it is currently unknown how rapid cooling after heatstroke affects the health of species that share a similar physiology with humans such as pigs. Although we confirmed that rapid cooling after heatstroke in pigs reduced rectal temperature, intestinal core body temperature was unaffected and remained above euthermic levels during heatstroke recovery. As a result, intestinal damage and circulating endotoxin and cytokines were increased in rapidly cooled compared to gradually cooled pigs. In summary, rapid cooling after heatstroke reduced rectal temperature but had no effect on intestinal temperature and this may be linked to increased intestinal damage and a greater systemic inflammatory response.

Technical Abstract: Acute hyperthermia can result in mortality if recovery is not appropriately managed. The study objective was to determine the effects of heatstroke recovery methods on the physiological response in pigs. In four repetitions, 36 male pigs (88.7 ± 1.6 kg BW) were exposed to thermoneutral conditions (TN; n = 3/rep; 19.5 ± 0.1°C) for 6 h, or HS (36.4 ± 0.1°C) for 3 h, followed by a 3 h Recovery period of rapid cooling (HSRC; n = 3/rep; rapid TN exposure and ice water dousing) or gradual cooling (HSGC; n = 3/rep; gradual decrease to TN). Rectal (TR) and gastrointestinal-tract temperatures (TGI) were obtained every 15 min. In Repetitions 1 and 2, blood was collected at 60 and 180 min during HS, and 30 and 60 min during Recovery, and then pigs were euthanized at 180 min for tissue collection. HS increased (p < 0.01) maximum TR (40.7°C) and TGI (41.5°C) compared to TN treatment (38.9 and 39.3°C, respectively). Recovery reduced TR (p < 0.01; 0.4°C) in HSRC versus HSGC pigs, but TGI was similar (40.7°C). HSRC reduced (p < 0.01) villus height to crypt depth ratio in the duodenum (34%) and ileum (46%) versus HSGC pigs. Serum [LPS] was greater in HSRC pigs (p = 0.04; 68.5 and 52.4%, respectively) compared to TN and HSGC pigs, and [TNFa] tended to be greater (p = 0.06; 41.2%) compared to HSGC pigs during Recovery. In summary, rapid cooling reduced TR but had no effect on TGI and this may be linked to increased intestinal damage and systemic inflammatory response.