U. Kreutzer et T. Jue, METABOLIC RESPONSE TO OXYGEN LIMITATION IN ARENICOLA-MARINA AS DETERMINED WITH THE H-1-NMR SIGNALS OF MYOGLOBIN, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, 120(1), 1998, pp. 127-132
During hypoxic stress many intertidal animals preserve their functiona
l integrity by down regulating their energy utilization and by compens
ating the aerobic energy loss with anaerobic ATP production. Arenicola
marina is a well established invertebrate model in which aerobic meta
bolism starts to decline well above the critical oxygen point. Even th
ough the A. marina oxygen consumption profile versus ambient O-2 is we
ll characterized, the underlying biochemical mechanism regulating intr
acellular oxygen metabolism in vivo remains unclear. Recently,H- 1 NMR
has opened an approach to observe tissue oxygenation with the signals
of myoglobin (Mb). The deoxy Mb proximal histidyl NdeltaH and the oxy
Mb valine Ell gamma CH3 signals are detectable in tissue and along wi
th the Mb p(O-2)(50), can yield a quantitative measurement of the intr
acellular oxygen level. The A. marina Mb proximal histidly NdeltaH sig
nals appear at 93.4 and 92.5 ppm (25 degrees C), respectively, while t
he corresponding valine Ell gamma CH3 signals appear at - 2.83 and - 2
.74 ppm. As the p(O-2) declines, MbO(2) saturation and MVO2 decrease.
However, phosphotaurocyamine concentration remains unaltered until the
MbO(2) saturation falls below 33%. The data suggest that the critical
intracellular p(O-2) value is below 0.1 kPa (1 torr). The study estab
lishes the H-1 NMR technique as an approach to measure the intracellul
ar p(O-2) with an oxygenated state marker and presents the interrelati
onship between oxygen and the metabolic adaptation during hypoxic stre
ss. (C) 1998 Elsevier Science Inc. All rights reserved.