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A new method for measuring mucociliary tracheal transport rates (MTTR's) is described. An aqueous aerosol containing albumin microspheres labeled with 99mTc was inhaled in such a manner that it was deposited in local concentrations in the large airways. These boli of microspheres were transported up the trachea and their MTTR's measured using a gamma camera. MTTR's were measured in 42 healthy nonsmoking adults (32 men and 10 women, mean age 28 yr). The mean MTTR's appeared to be log normally distributed with a geometric mean of 3.6 mm/min and a coefficient of variation of 75%. The MTTR's of men and women were similar. Each individual's short-term coefficient of variation was 25%. Twenty-two repeat studies 1 wk to 15 mo apart showed the variation within individuals was less than between individuals. The parasympatholytic drug, atropine (0.6 mg iv) decreased MTTR's for at least 3 h. Inhalation of the sympathomimetic drug, Th1165a increased MTTR's. Chronic and acute smoking did not appreciably change the MTTR'S. 相似文献
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Aging among elite distance runners: a 22-yr longitudinal study 总被引:5,自引:0,他引:5
Trappe S. W.; Costill D. L.; Vukovich M. D.; Jones J.; Melham T. 《Journal of applied physiology》1996,80(1):285-290
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Summary Evidence is presented that adaptation of yeast cells to ethanol results in a reduced loss of cell viability induced by exposure to that agent. In line with earlier work, an exponential model is shown to apply when the concentration of ethanol exceeds a critical value, beyond which cell growth cannot occur. Such an exponential model is consistent with the absolute theory of reaction rates. Adaptation of yeast cells to 7% w/v ethanol lowers the specific rate of cell death at various ethanol concentrations by a factor of some 40 fold compared to a non-adapted culture. 相似文献
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