Cleansing Cilia

Man has been breathing with lungs for a million years. Men have been studying the lungs's physiology for nearly 5.000 years. But not until Radiologist Alfred Ernest Barclay* took to blowing bismuth and powdered glass down the windpipes of cats was one of the lungs's important protective devices thoroughly studied. Last week his findings were published in the American Journal of Roentgenology.

At Oxford's Nuffield Institute for Medical Research, Dr. Barclay has recently explored the uttermost crannies of the living lungs. Notable result was a complete description of "the normal escalator action" by which the lungs constantly expel dry dust that is inhaled. Dr. Barclay made his observations on the lungs of anesthetized cats, which breathe at 30 respirations a minute (almost as slowly as man).

The walls of most of the throat, of the windpipe and its branches (bronchi and bronchioles) are covered with fine, threadlike filaments called cilia, which continually move, waving their tips with an upward motion. When bismuth powders or pulverized lead glass were blown deep into the lungs of anesthetized cats, Dr. Barclay and his associates found that the dust in dry form remained in the windpipe and its branches, never penetrating into the little sacs (alveoli) which absorb oxygen from the air and eliminate carbon dioxide from the blood. They could see by X-ray the foreign particles moving from the base of the lungs up & out. The movement they discovered was spiral and (viewed from above) clockwise. Particles traveled 1 1/2 inches per minute within a cat's windpipe. When administered in oil or other fluids, the particles quickly reached the alveoli, were not completely excreted except over a period of weeks. The researchers found that the cilia, to remove dust effectively, must be covered with a "blanket" of mucus. The cilia kept this mucus moving up & out of the lungs all the time.

Significant for human beings who live in dusty cities, especially for those who work in dusty factories, mills or mines, were the conclusions of Dr. Barclay & associates. "Healthy lungs should have no difficulty in coping with the minute amounts that are inhaled in the most dusty atmospheres, provided the subject is given an adequate rest period away from these atmospheres." But people who live in damp and dirty cities have no such assurance, because ''it seems possible that a moist atmosphere might tend to agglomerate particles of suitable dusts, and turn them into a semifluid, which could interfere with ciliary action."

*Collaborating were Oxford's Medical Dean Kenneth James Franklin and Dr. R. G. Macbeth.

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