Hperthermia (heat stroke) can cause death, particularly as a result of the splanchnic dilation that precedes vascular collapse.

In the February issue of American Journal of Physiology - Heart and Circulation researchers from University of Iowa demonstrate that hyperthermia stimulates splanchnic xanthine oxidase production of reactive oxygen species. This is turn leads to the activation of metals that limit heat tolerance by promoting circulatory and intestinal barrier dysfunction.

David Hall and colleagues studied anaesthetised rats exposed to an ambient temperature of 40°C and found that elevating colonic temperature from 37°C to 41.5°C reduced splanchnic blood flow by 40%. This stimulated the production of the radicals ceruloplasmin, semiquinone, and penta-coordinate iron(II) nitrosyl-heme (heme-·NO). Portal endotoxin concentration rose from 28 pg/ml to 59 pg/ml (p < 0.05) (Am J Physiol 2001, 280:H509-H521).

Nitric oxide syntethase II, the diamine oxidase antagonist aminoguanidine, the superoxide anion scavenger superoxide dismutase and the...

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