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At least 577 records · Page 32Linked to original sources
PubMed1995

Poor ventilatory response to mild hypoxia may inhibit acclimatization at moderate altitude in elderly patients after carotid surgery.

Peripheral chemoreceptors (carotid bodies) are the main sensing organs for hypoxaemia. During carotid surgery, the carotic body in the bifurcation of the common carotid artery is often involved and damaged or destroyed. Animals lose their ability to adapt to high altitude after experimental denervation of the carotid bodies. The objective of our study was to evaluate the ability of human patients to adapt to moderate altitude after single side carotid surgery. Blood gas analysis at rest at 171 m and after car and cable car transport to 1600 m before and after carotid surgery was performed. Mean(s.d.) paO2 decreased insignificantly from 74.8(3.56) at 171 m altitude to 71.6(2.07) at 1600 m (P = n.s.), means(s.d.) paCO2 decreased significantly from 36.2(2.86) to 31.4(2.7) mmHg (P < 0.05) before carotid surgery. Months after surgery, a significant drop in paO2 occurred after identical passive exposure to moderate altitude: mean(s.d.) paCO2 at 171 m 74.4(3.65) mmHg, at 1600 m 65.8(3.70) mmHg (P < 0.01), paCO2 did not change significantly. Mean(s.d.) paCO2 at 171 m: 36.0(2.35), at 1600 m 36.2(2.86) mmHg (P = n.s.). Although the sample investigated was small, after single side carotid surgery patients seem to lose their ability for satisfactory ventilatory response to acute exposure to moderate altitude. This is of possible alpine medical importance.

Acclimatization↗
PubMed1987

Effect of acetazolamide on blood gases and 2,3 DPG during ascent and acclimatization to high altitude.

Blood gases and red cell 2,3 DPG concentrations were measured during ascent and a stay for 6 days at 4846 m in 20 subjects. Acetazolamide improved Pa,O2 and reduced pH and Pa,CO2. 2,3 DPG concentrations were lower in the acetazolamide group during ascent and at high altitude. However, 2,3 DPG concentrations were significantly greater at high altitude in both the acetazolamide and placebo groups compared with low altitude. The acetazolamide group remained different from the placebo group during the stay at high altitude with higher Pa,O2, lower PaCO2, lower pH and lower 2,3 DPG concentrations.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Heme oxygenase activity in fetal and adult sheep is not altered by acclimatization to high altitude hypoxia.

Hypoxic stress has been reported to induce the expression of stress proteins such as heme oxygenase (HO), which catalyze the breakdown of heme to generate biliverdin, ferrous iron, and carbon monoxide. These degradation products play a role in the regulation of a variety of processes such as vascular tone, inflammation, and central nervous system function. In mammals, there are 2 catalytically functional HO isozymes, HO-1 (inducible) and HO-2 (constitutive). HO-1 expression is regulated by an array of nonphysiological and physiological stimuli including acute hypoxemia. As relatively little is known of the HO response to prolonged hypoxia in whole animals other than small laboratory rodents, the aim of this work was to examine the effect of long-term hypoxia on total HO activity in fetal and adult ovine tissue. Sheep were maintained at high altitude (3820 m), after which the following tissues were harvested from near-term fetal and non-pregnant ewes for in vitro measurement of HO activity: left ventricle, renal papilla, lung apex, pulmonary artery, carotid artery, mesenteric artery, placental cotyledon, spleen, and brain frontal cortex. There were no significant differences between HO activities in tissues from hypoxic fetal and adult sheep compared with their normoxic controls. Fetal heart HO activities were higher than those of adult tissue (p < 0.05), whereas adult spleen HO activity was significantly higher than that of fetal tissue (p < 0.05). In conclusion, these data indicate that long-term exposure to high altitude hypoxia does not have a persistent effect on HO activity in ovine tissues. Also, except for the spleen where there is a high expression of HO-1 under normal conditions, tissue HO activity is correlated with the expression of HO-2, the constitutive isozyme.

Acclimatization↗