Effect of lifelong nicotine inhalation on bone mass and mechanical properties in female rat femurs

As tobacco smoking has been identified as a risk factor in the development of osteoporosis, possible deleterious effects of nicotine inhalation on bon e mineral density (BMD) and mechanical properties of the femur in female ra ts were studied. Female Sprague Dawley rats were exposed to nicotine vapour 20 hours a day 5 days a week for 2 years. The nicotine concentration in th e inhaled air was kept at a lever, giving a plasma nicotine concentration e xceeding that of heavy smokers. Throughout the study, the nicotine-exposed rats weighed approximately 10% less than the control rats. At the end of th e study the rats were anesthesized and blood was collected by heart punctur e for determination of nicotine in plasma. Both femurs were resected and sc anned by dual X-ray absorptiometry (DXA). There was no difference in BMD be tween control rats (n = 7) and nicotine-exposed rats (n = 23) (mean 0.216 /- 0.021 g/cm(2) and 0.210 +/- 0.014 g/cm(2), respectively (P = 0.19)). The left femur was used for mechanical testing of the shaft and the neck. No s ignificant difference could be demonstrated in ultimate bending moment, ult imate energy absorption, stiffness, or deflection between the two groups. I n conclusion, no negative effects of nicotine inhalation on the femurs of f emale rats were found.