Age and gender affect soot's toxic impact.

From second to second, blood vessels must alternately constrict and dilate to regulate blood flow. That ability can diminish markedly in rodent vessels exposed to an oily constituent of diesel soot, researchers report.

The team took arteries from rats' thighs and exposed them to the soot chemical phenanthraquinone.

Vessels came from female rats that were 6, 14, and 24 months old--comparable to girls approaching puberty, women in their reproductive years, and women over 65 years of age. Half of each age group of animals had undergone ovary-removal surgery lowering their production of sex hormones and simulating that of postmenopausal women. Vessels of male rats 6 and 24 months old were also tested.

The soot agent rendered vessels from 24-month-old males and from all females without ovaries unable to dilate, says study leader Timothy R. Nurkiewicz of the West Virginia University School of Medicine in Morgantown. In 6-month-old males and 14-month-old females with ovaries, phenanthraquinone reduced dilation by 65 percent. Only the youngest females showed no vessel impairment from the chemical.

Such findings reinforce the need to consider age and gender when evaluating the toxicity of pollutants, says Nurkiewiez. He presented the findings May 1 at the Experimental Biology meeting in Washington, D.C.--J.R.