DOES CLONIDINE BLOCK DECREASE IN TISSUE OXYGEN CAUSED BY SMOKING?

吸烟已被证明会降低皮下组织氧（PsqO2）。这被认为是由于尼古丁的交感神经效应。可乐定是一种中枢作用的α 2肾上腺素能激动剂，可减少交感神经输出。因此，这项研究正在进行，以观察可乐定是否通过阻断吸烟引起的交感神经输出，可以防止或减少PsqO2的下降。为了实现这一目标，健康志愿者将被要求吸烟，并测量PsqO2的下降。将允许大约一小时的间隔。尼古丁的影响会逐渐消失。随后给予可乐定或安慰剂。两小时后，在可乐定血药浓度达到峰值时，受试者将被要求再次吸烟，并监测皮下氧浓度。一周后，这项研究将在同一受试者身上重复进行，他们将接受第一轮没有接受的另一种药物。两种药物将按随机顺序施用。使用安慰剂可以监测连续吸烟对Psq02的影响。我们打算在GCRC中进行所有研究程序和测量。受试者将在研究的两天上午入院，并在下午晚些时候出院。这项研究每天将花费8个小时。

Smoking has been shown to decrease subcutaneous tissue oxygen (PsqO2). This is thought to be due to the sympathomimetic effects of nicotine. Clonidine is a centrally acting alpha 2 adrenergic agonist which decreases sympathetic output. This study is thus being performed to see if clonidine, by blocking the sympathetic output caused by smoking, can prevent or decrease the drop in PsqO2. To achieve this, healthy volunteers will be asked to smoke and the decrease in PsqO2 measured. An interval of approximately 1 hour will be allowed for the. effects of nicotine to wear off. Clonidine or a placebo drug will be subsequently administered. Two hours later at peak plasma concentration for clonidine, the subjects will be asked to smoke again and subcutaneous oxygen tension will be monitored. This study will be repeated a week later on the same subject, who will receive the other drug that they did not receive in the first round. Both drugs will be administered in a randomized order. The use of placebo allows the effect of consecutive smoking sessions on Psq02 to be monitored. We intend to carry out all study procedures and measurements in the GCRC. Subjects will be admitted in the morning on both days of the study and discharged late afternoon. The study will take 8 hours on each day.