SUBLETHAL EFFECTS OF PENTACHLOROPHENOL AND HYPOXIA ON RATES OF ARGININE KINASE FLUX IN RED ABALONE (HALIOTIS-RUFESCENS) AS MEASURED BY P-31MAGNETIZATION SATURATION-TRANSFER NMR

Previous studies have demonstrated P-31 nuclear magnetic resonance (NM R) to be a sensitive technique in assessing biochemical effects of sub lethal toxicant exposure in live, intact marine organisms. This study builds upon previous work using P-31 NMR magnetisation saturation tran sfer techniques to determine rates of exchange through the arginine ki nase (AK) reaction. The objective of this study is to compare rates of AK flux during exposure of red abalone (Haliotis rufescens) to pentac hlorophenol (PCP; an uncoupler of mitochondrial oxidative phosphorylat ion) or hypoxia. Utilizing a teflon and silicon flow-through exposure system, pseudo-first-order rate constants are determined for the ATP-f orming direction of the AK reaction during 2-h exposure and 6-h recove ry of abalone to 1.2 ppm PCP, or hypoxia by the cessation of water flo w. Preliminary results show that AK rates increase during hypoxia, pea king in the first hour of resumed water flow, indicating an increased metabolic demand for ATP production through phosphoarginine hydrolysis during hypoxia and the initial stages of recovery. In contrast, AK fl ux rates remain low during PCP exposure and several hours into the rec overy, period, even though the toxic responses, i.e. changes in inorga nic phosphate and phosphoarginine concentration, are similar for both exposure regimes. These results provide supporting evidence for a rece ntly described new mechanism of action of PCP by AK inhibition. This s tudy demonstrates a sensitive new method for evaluating sublethal effe cts of toxicants on a vital biochemical market in intact marine organi sms. Copyright (C) 1996 Elsevier Science Ltd