A chemical cousin of Teflon is showing promise as a blood substitute in animals and may one day help stroke patients, a researcher says.

"It's chemically pretty inert - pretty non-toxic - (and) could be stored fairly easily without fear of contamination with virus or bacteria or dirt," said Robert A. Linsenmeier, associate professor of biomedical engineering and neurobiology and physiology at Northwestern University.The blood substitute is made of a class of chemicals called fluorocarbons. Teflon is also a fluorocarbon, a carbon-based compound in which most or all hydrogen ions have been replaced by fluorine atoms, Linsenmeier said.

Different fluorocarbons have different physical properties, he said, adding that the blood substitute he and his colleagues are testing is a thick, milky fluid made by Alliance Pharmaceutical Corp. of San Diego.

In stroke patients, doctors may one day be able to inject some of the artificial blood soon after the stroke and boost the oxygen supply to affected brain tissue.

The findings in tests on eight cats by Linsenmeier and Thomas K. Goldstick, professor of chemical engineering and biomedical engineering, were to be presented this month by their co-researcher, Rod Braun, of the American Institute of Chemical Engineers in Chicago.

Now, only one form of artificial blood is approved by the Food and Drug Administration for use in humans - a fluorocarbon emulsion called Fluosol.