Metabolic response in Arenicola marina to limiting oxygen as reflected in the 1H-NMR oxymyoglobin signal.

Many intertidal animals can endure prolonged periods of environmental stress and have developed strategies to preserve a functioning energy state in the cell. Recent 1H/31P-NMR techniques have allowed investigators to monitor directly mammalian tissue metabolism in vivo. In particular, the signals of myoglobin (Mb) offer a unique opportunity to explore the intracellular oxygen-partial-pressure [p(O2)] interaction in Arenicola marina, a standard model to study hypoxia tolerance in invertebrates. The present study reveals that the 1H-NMR MbO2 signal at -2.9 ppm is detectable in tissue and reflects directly the oxygenated state. As the p(O2) declines, MbO2 saturation and oxygen consumption decrease. However, phosphotaurocyamine concentration remains unaltered until the MbO2 saturation falls below 33%. The extracellular to intracellular p(O2) gradient appears substantial. 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.