Effects of hypoxia and toxicant exposure on phosphoarginine, intracellular pH, and free Mg2+ in abalone as measured by 31P-NMR
The effects of hypoxia, sodium azide and pentachlorophenol (PCP) exposure on high-energy phosphorylated compounds, intracellular pH (pH(i)) and intracellular free Mg2+ (Mg(f)) in intact red abalone (Haliotis rufescens) were determined using 31P-NMR. Abalone made hypoxic by bubbling sea water with N2 showed modest changes in phosphoarginine (PA) and inorganic phosphate (P(i)) concentrations, no significant changes in pH(i) and a moderate decrease in Mg(f) that was not statistically significant. Azide (50 mg/l) exposed animals displayed severe declines in PA dropping to 0.53 of reference values, coupled with large increases in P(i) to 10.66 times resting concentrations that occurred just after the 2-hr exposure period. pH(i) also showed significant declines from a resting value of 7.17-7.06 (P < 0.05) but fully recovered by the end of the 6-hr clean seawater recovery period, whereas Mg(f) concentrations declined slightly during the exposure period but increased by 18% at the end of the recovery period relative to reference Mg(f). PCP (1.2 mg/l) exposed animals displayed similar increases and declines in P(i) and PA, respectively, as did azide-exposed animals by the end of the exposure period, but recovery was much slower and occurred in a bimodal fashion with some animals completely recovering at the end of 6 hr and others essentially stabilized at the end of the exposure period and did not show any significant changes during the recovery period.
