Preliminary studies of urinary hydroxyproline levels in rodents and in smokers.

Groups of rats were exposed to four dilutions of cigarette smoke over a period of our weeks. Compared to the control (untreated) group of animals, the 24-hour hydroxyproline output (relative to creatinine) was lower for all dilutions of smoke and showed a negative dose-response relationship. In human smoking studies, in which groups of 20 male subjects and 20 female subjects were switched between various cigarettes for periods of 2 weeks, hydroxyproline output (relative to creatinine) for each sex did not change with increasing nicotine uptake although the outputs for men and women were significantly different.