Biochemistry of Submarine and Diving Stress. 1. Lactate-Pyruvate and Redox State Responses of Blood and Tissue in Chronic Hypercapnia
Abstract
Lactate and pyruvate concentrations were measured in blood and various tissues of guinea pigs exposed to 15% CO2 in 21% O2, balance N2, for varying periods of time up to one week. Acute exposure resulted in reduction of lactate/pyruvate ratios (L/P) of blood, heart, and muscle but not liver. Blood L/P further decreased after one day of exposure and slowly increased during the chronic phase of respiratory acidosis. Heart L/P returned to control values by six hours while muscle L/P remained depressed for the duration of hypercapnia. Since L/P reflect the redox state of the free glycolytic nicotinamide-adenine dinucleotide couplet, the redox state, NAD(+)/NADH was calculated from the L/P and pH of blood for the various periods of hypercapnia. During acute hypercapnia NAD(+)/NADH increased in blood markedly indicating the existence of a more oxidized state during this period. Chronic hypercapnia returned blood NAD(+)/NADH toward initial values suggesting a normalization of glycolytic metabolism. The observed differences in L/P in the various tissues are apparently related to the different CO2 buffering capacities of tissues.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 22, 1971
- Accession Number
- AD0734120
Entities
People
- Karl E. Schaefer
- Michael J. Jacey
Organizations
- Naval Submarine Medical Research Laboratory