Liver function is being monitored at Patuxent by the indocyanine green 

 clearance technique. This technique is a sensitive measure of hepatic function 

 in which removal of an injected dye from the blood is carried out entirely 

 by the liver. In addition, tissue-specific enzymes that appear in the circulation 

 because of organ damage are being measured, as well as triglyceride concentra- 

 tions and cholesterol concentrations. For the past five months, mallard ducks 

 {Anas platyrhynohos) have been fed a mixture of 10 aromatic hydrocarbons found 

 in Southern Louisiana crude oil (SLC) at concentrations equivalent to the 

 aromatic content of 2,500 and 25,000 ppm SLC. Preliminary results from this 

 continuing study indicate that the ingestion of large amounts of aromatic 

 hydrocarbons results in increased hepatic function with no biochemical evidence 

 of cellular damage (Patton, unpublished data). 



In another study at Patuxent, mallard ducklings were fed 250, 2500, 25,000, 

 and 50,000 ppm of SLC mixed in feed. After 8 weeks, the body weights of 

 ducklings fed 50,000 ppm of crude oil and the liver and spleen weights of 

 ducklings fed 25,000 and 50,000 ppm of crude oil in feed were significantly 

 different from those of the controls (Szaro, unpublished data) (Table 1). 

 The increased liver size and decreased spleen size suggest hyperactivity of 

 the liver and adrenal gland. 



Table 1. Body, liver, and spleen weights of mallard ducklings fed 

 Southern Louisiana crude oil from hatching until 8 weeks old 



Different from the control (P 

 liver and spleen weight, 10. 



< 0.05). Sample sizes: body weight, 50; 



Waterfowl exposed to salt water increase the water taken in by the small 

 intestine to compensate for osmotic water loss from tissues (Crocker and Holmes 

 1971). Crocker et al . (1974) used an in vitro system of sacs of small intestine 

 and found that ducklings dosed with 0.2 ml of Santa Barbara crude oil prior 

 to exposure to salt water failed to absorb water at a rate equal to undosed 

 ducklings. Using similar techniques, they showed that the increase in intestinal 

 water uptake that developed during prolonged exposure to salt water was abolished 

 after a single dose of crude oil. Dr. Neil Holmes, University of California, 

 Santa Barbara, has contracted with us to extend these studies with mallard 

 ducks. Initially, his group will study electrolyte balance and adrenal hormone 

 responses in mallards adapted to sea water and fed SLC in their food. 



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