[Acute effect of 7% CO2 breathing on lactate, pyruvate and ketone body metabolism in healthy subjects].
Although the effect of hypoxia on the tissue metabolism is well discussed, little is known about hypercapnia. To investigate the effect of hypercapnia on metabolism, we studied 10 normal subjects in a condition of acute normoxic hypercapnia, while they breathed a mixture of gases: 7% CO2, 21% O2 and the remainder, N2. Lactate, pyruvate, nonesterified fatty acid (NEFA), and ketone bodies were measured by taking blood samples before the study (C), when end tidal CO2 reached its peak level (P), and when end tidal CO2 returned to normal (R). Pyruvate decreased from 0.66 +/- 0.17 mg/dl from (C) to (P), and reached its lowest value in (R). A significant decrement was found in (R) compared with (P) (p < 0.05). Lactate increased gradually, but not significantly, from (C) to (R), while the lactate/pyruvate ratio increased significantly from (P) to (R). No significant change was found in the acetoacetate/3-hydroxybutylate ratio. These results suggest that acute hypercapnia may affect the metabolism via the mitochondria, and we conclude that hypercapnia may play an important role in the disruption of tissue metabolism in man.
Joon
S J
SJ
Second Department of Internal Medicine, Toho University School of Medicine, 6-11-1 Omori-nishi, Ota-ku, Tokyo 143-8541.
D000208:Acute Disease; D000328:Adult; D002245:Carbon Dioxide / Q000009:adverse effects*; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism*; D007657:Ketone Bodies / Q000097:blood*; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008928:Mitochondria; D019289:Pyruvic Acid / Q000097:blood*
D007657:Ketone Bodies; D002245:Carbon Dioxide; D019344:Lactic Acid; D019289:Pyruvic Acid