We all know — or at least should know — about alcohol tolerance and its accompanying dangers. The more some people drink, the more it takes for them to get ‘high’. The body, unfortunately, does not take notice of this raising of the, er, bar and succumbs to the batterings that accompany excessive drinking even though the drinker may no longer find it ‘excessive’. Now Japanese researchers have found that a very similar thing happens for smokers.
Tobacco plants have evolved a chemical called nicotine, which when it enters a smoker’s body, latches on to certain molecular receptors in the outer membrane of nerve cells. It is this stimulation of the nerve cells that produces a pleasant sensation for smokers. The nicotine also results in small changes in the way nerves connect to each other, resulting in a new-found discomfort if the supply of nicotine is not forthcoming. In simple terms, this is nicotine addiction. Some smokers, however, need more nicotine than others for the modified nerve paths to be stable. This depends on the kind of a particular enzyme, CYP2A6, that a person has in his body. The function of CYP2A6 is to convert nicotine into the less harmful cotinint that is excreted. And the kind of CYP2A6 you get is in turn determined by a particular gene — which some people lack altogether. Thus, the number of cigarettes you smoke depends on your genes. Which is another way of saying: I can’t help it that I’m a chimney.
Whether that excuse works for the betterment of your social or marital life, however, is another matter altogether.