Influence of acute hypoxia combined with nitrous oxide on cardiovascular variability in conscious hypertensive rats

Sugimura, Mitsutaka; Hanamoto, Hiroshi; Sato, Aiji; Morimoto, Yoshinari; Taki, Kunitaka; Kudo, Chiho; Niwa, Hitoshi

doi:10.1016/j.autneu.2010.04.008

Cited by 7 publications

(3 citation statements)

References 45 publications

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“… 45 , circulatory hypoxia is sensed through carotid bodies located in the carotid artery 46 , 47 that, under non-hypometabolism-inducing, hypoxic conditions, relay arterial O 2 tension ( P a O 2 )-related information to the brain. The brain subsequently (hyper)activates certain physiological functions to remediate the hypoxia 48 , which include panting 49 – 53 and tachycardia 53 , 54 . How this is blocked during the induction of anapyrexia is currently unclear.…”

Section: Discussionmentioning

confidence: 99%

Exogenous hydrogen sulfide gas does not induce hypothermia in normoxic mice

Hemelrijk

Dirkes

Velzen

et al. 2018

Sci Rep

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Hydrogen sulfide (H2S, 80 ppm) gas in an atmosphere of 17.5% oxygen reportedly induces suspended animation in mice; a state analogous to hibernation that entails hypothermia and hypometabolism. However, exogenous H2S in combination with 17.5% oxygen is able to induce hypoxia, which in itself is a trigger of hypometabolism/hypothermia. Using non-invasive thermographic imaging, we demonstrated that mice exposed to hypoxia (5% oxygen) reduce their body temperature to ambient temperature. In contrast, animals exposed to 80 ppm H2S under normoxic conditions did not exhibit a reduction in body temperature compared to normoxic controls. In conclusion, mice induce hypothermia in response to hypoxia but not H2S gas, which contradicts the reported findings and putative contentions.

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Section: Discussionmentioning

confidence: 99%

Exogenous hydrogen sulfide gas does not induce hypothermia in normoxic mice

Hemelrijk

Dirkes

Velzen

et al. 2018

Sci Rep

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“…This discrepancy is probably due to the effect of ketamine anesthesia. Whereas conscious mammals, including humans and rats, react to inspired hypoxia with an increase in heart rate, hypoxia-in conjunction with ketamine anesthesia-generally appears to reverse this reaction (13,36,47).…”

Section: Pulmonary Wdrmentioning

confidence: 99%

The combination of theophylline and endothelin receptor antagonism improves exercise performance of rats under simulated high altitude

Radiloff

Zhao

Boico

et al. 2012

Journal of Applied Physiology

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Decreased physical performance is a well-known consequence of rapid ascent to high altitude. Hypoxic pulmonary vasoconstriction (HPV) potentially limits cardiac output and systemic blood flow, thus preventing successful adaptation to rapid ascent. We hypothesized that pharmacological enhancement of the heart rate with theophylline, combined with reversal of HPV via endothelin blockade, could increase exercise performance at high altitude. Female Sprague-Dawley rats were treated with combinations of 1) theophylline, 2) the endothelin receptor antagonists sitaxsentan/ambrisentan, and/or 3) phosphodiesterase-5 inhibitor sildenafil and exposed to either a simulated high altitude (4,267 m) or 12% oxygen. Exercise capacity, peripheral blood flow, hemodynamics, and pulmonary leak were examined. Combination treatment with theophylline and endothelin blockade, but not with the respective single compounds, significantly prolonged run-to-fatigue time under simulated high altitude. No such efficacy was found when theophylline was combined with sildenafil. Neither theophylline nor sitaxsentan or their combination influenced breathing rates and hemoglobin oxygen saturation. Whereas under hypoxia, theophylline significantly increased muscular blood flow, and sitaxsentan increased tissue oxygenation, the combination improved both parameters but in a reduced manner. Under hypoxia, the combination treatment but not the single compounds significantly enhanced pulmonary arterial pressure compared with controls (13.1 ± 6.3 vs. 11.9 ± 5.2 mmHg), whereas mean arterial pressure remained unaffected. Pulmonary wet-to-dry weight ratios were unaffected by combination treatment. We conclude that concomitant dosing with a cardiac stimulant and endothelin antagonist can partially reverse loss of physical performance capacity under hypobaric hypoxia, independent from improving blood oxygen saturation.

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“…5 Acute exposure to nitrous oxide may be connected with cardiovascular variability. 6 Chronic exposure to nitrous oxide is associated with decrements of lung function, hematological problems, marrow suppression and neurologic symptoms. 7,8 Nitrous oxide has been certified for use as a food additive to generate foam.…”

Section: Introductionmentioning

confidence: 99%

Death caused by addictive inhalation of nitrous oxide

et al. 2011

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Intoxications with nitrous oxide have been, and still are, a rarity in forensic medicine. Apart from accidental overdose during hospital procedures, intoxication with this gas is the result of voluntary inhalation. We report the fatal case of a 32-year-old male who died during inhalation of nitrous oxide from whipped dairy cream cans and hint on the role of the internet in creating new behaviors among drug addicts. We rely on the autopsy report from the Department of Forensic Medicine, Pomeranian Medical University in Szczecin, on laboratory tests, and court files. Neither the autopsy nor the toxicologic and histopathologic tests disclosed the exact cause of death. However, circumstances in which the body was discovered were indicative that death resulted from cardiorespiratory failure. The present case is interesting with regard to its rarity, diagnostic difficulties and potential harm from nitrous oxide used by the food industry.

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Influence of acute hypoxia combined with nitrous oxide on cardiovascular variability in conscious hypertensive rats

Cited by 7 publications

References 45 publications

Exogenous hydrogen sulfide gas does not induce hypothermia in normoxic mice

Exogenous hydrogen sulfide gas does not induce hypothermia in normoxic mice

The combination of theophylline and endothelin receptor antagonism improves exercise performance of rats under simulated high altitude

Death caused by addictive inhalation of nitrous oxide

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