Tobacco cigarette smoking and patellar reflex depression

One hundred fifteen young men served as subjects to determine the effects of smoking cigarettes of differing nicotine content on the patellar reflex. Each volunteer smoked 2 of the same kind of cigarettes in a 4 minute period with an interval of 25 minutes between. The patellar reflex was elicited automatically every 2 seconds by a reflex hammer attached to a solenoid. The reflex was recorded with the use of a strain gauge transducer and the electromyogram of the ipsilateral quadriceps femoris muscle. A negligible depression was produced by smoking a nicotine‐free lettuce cigarette. A low‐nicotine tobacco cigarette showed approximately 45 per cent depression within 5 minutes compared with a 67 per cent depression after smoking a high‐nicotine cigarette. The depression caused by the second cigarette was comparable in degree and duration to the effect of the first cigarette. No accumulative or tachyphylactic effect was observed. It is concluded that tobacco smoking produces a remarkable, short‐term depression of the human skeletal‐motor system. The depression of the patellar reflex seems to be related to the nicotine content of the cigarette smoked.