Interactive effects of pentachlorophenol and hypoxia in the abalone ( Haliotis rufescens) as measured by in vivo 31P NMR spectroscopy

Abstract

The effects of hypoxia and pentachlorophenol (PCP) were investigated in red abalones ( Haliotis rufescens) using flow-through exposure and in vivo 31P nuclear magnetic resonance spectroscopy (NMR). Following acclimation to clean seawater, three abalones were separately exposed to a 6-h sublethal concentration of PCP (1.2 mg 1 −1) until the spectral resonance for inorganic monophosphate (P i) was half-height to that of phosphoarginine (PA); the endpoint assured that all individuals were metabolically equivalent at the start of air exposure. They were exposed to clean seawater for 2 h to allow the effects from PCP to stabilize, then air for 45 min, and finally clean seawater for 15 h to check recovery. The effects of PCP in foot muscle included a decrease in the concentrations of PA and adenosine triphosphate ([PA] and [ATP], respectively), an increase in P i, and a decrease in intracellular pH (pH i). Upon air exposure, [PA] and pH i rapidly declined further, [P i] increased, and [ATP] did not change; the magnitudes were similar to those from emergence alone. After resubmergence, both [PA] and [P i] recovered rapidly from the effects of hypoxia, but slowly from those of PCP. While pH i initially declined further, both [ATP] and pH i recovered to near-initial levels after 15 h. In general, the metabolic effects of hypoxia did not change upon pretreatment with PCP; the biochemical interaction of the two factors was additive. Another three abalones were separately exposed to PCP at an environmentally relevant concentration of 120 μg 1 −1 for 6 h, air for 1 h, then the same PCP concentration for 2.5 h to check recovery. At the lower concentration, PCP produced no discernable effects, and those of hypoxia were similar to those without PCP. Since PCP produced no additional effects with or without hypoxia, it does not significantly impact red abalones at currently measured environmental concentrations. Use of in vivo NMR allows measurement of the interactive effects of multiple stress factors in live aquatic organisms, allowing assessment of the actual environmental effects of pollutants in the laboratory.