During hypoxic stress many intertidal animals preserve their functional integrity by down regulating their energy utilization and by compensating the aerobic energy loss with anaerobic ATP production. Arenicola marina is a well established invertebrate model in which aerobic metabolism starts to decline well above the critical oxygen point. Even though the A. marina oxygen consumption profile versus ambient O2 is well characterized, the underlying biochemical mechanism regulating intracellular oxygen metabolism in vivo remains unclear. Recently, 1H NMR has opened an approach to observe tissue oxygenation with the signals of myoglobin (Mb). The deoxy Mb proximal histidyl N(δ)H and the oxy Mb valine E11 γCH3 signals are detectable in tissue and along with the Mb p(O2)50, can yield a quantitative measurement of the intracellular oxygen level. The A. marina Mb proximal histidly N(δ)H signals appear at 93.4 and 92.5 ppm (25°C), respectively, while the corresponding valine E11 γCH3 signals appear at -2.83 and -2.74 ppm. As the p(O2) declines, MbO2 saturation and MVO2 decrease. However, phosphotaurocyamine concentration remains unaltered until the MbO2 saturation falls below 33%. The data suggest that the critical intracellular p(O2) value is below 0.1 kPa (1 torr). The study establishes the 1H NMR technique as an approach to measure the intracellular p(O2) with an oxygenated state marker and presents the interrelationship between oxygen and the metabolic adaptation during hypoxic stress.
|Original language||English (US)|
|Number of pages||6|
|Journal||Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology|
|State||Published - May 1 1998|
ASJC Scopus subject areas
- Molecular Biology