Meeting Abstract

P2.18  Jan. 5  Effects of Diltiazem and Lanthanum on Copper Inhibition of O₂ Consumption in Gill of the American Oyster, Crassostrea virginica. MCCOY, Kwanza*; COLLINS, Shanika; CARROLL, Margaret A.; CATAPANE, Edward J.; Medgar Evers College; Medgar Evers College; Medgar Evers College; Medgar Evers College catapane@mec.cuny.edu

Our oyster rehabitation studies showed that Crassostrea virginica transplanted to Jamaica Bay , NY accumulated copper. Mitochondria are sensitive to oxidative stress caused by metal toxicity. We studied effects of copper on 0₂ utilization in C. virginica using a YSI Micro-Biological Oxygen Monitor with continuos flow or micro-batch chambers. 5 or 50 mg of CuSO₄ decreased respiratory rates 12 and 32%, respectively. Oysters grown in Jamaica Bay or exposed to copper pretreatments were more sensitive to copper additions. 5 mg CuSO₄ decreased O2 utilization in excess of 34% and 50 mg caused complete inhibition. We now sought to determine if channel blockers would affect copper�s ability to depress mitochondrial respiration. Using micro-batch chambers we measured 0₂ consumption in the mitochondrial fraction from gill tissue. Copper reduced respiratory rates in them as previously shown. Pretreating the mitochondria with diltiazem blocked the copper inhibition, while pretreating with lanthanum did not. Lanthanum had a slight inhibiting effect of its own. The study demonstrates that the diltiazem is effective in blocking copper�s inhibitory effects on mitochondria and may be useful in blocking copper transport into tissues of other animals as well. The toxic effects of copper on gill mitochondrial could be of physiological significance to the growth and long-term health of oysters and other marine animals living in a copper polluted environment and a copper uptake blocker could be of benefit for preventing diseases caused by high serum copper levels in humans. This work was supported by grants 1R25GM62003 of NIGMS, 0516061071 of NYSDOE and 66288-0036 of PSC-CUNY. We thank Flower & Sons, Inc., Oyster Bay, NY for supplying oysters.