Nicotine limits cold adaptation

Cigarette smokers commonly find that they have a hard time keeping their hands and feet warm in frigid environments. Researchers at Yale University now find that nicotine, usually considered the culprit, may play only a partial role.

Kichang Lee and Gary W. Mack recruited 7 smokers and 10 nonsmokers for two rounds of a painful test: submersion of a hand in 5°C water for 40 minutes. Sensors monitored how the skin’s blood vessels responded. Although smokers had to refrain from lighting up for at least 16 hours prior to a test, each wore a nicotine patch during one of the tests. Nonsmokers underwent both of their tests nicotinefree.

Ordinarily, blood vessels respond to cold conditions by constricting to keep blood away from the cooling effect. Periodically, however, those vessels will briefly dilate, sending blood through the skin to keep the tissue from freezing.

At the Experimental Biology meeting in late April in Washington, D.C., Lee and Mack reported that regardless of whether a smoker was wearing a patch, his or her blood vessels exhibited a significant delay in dilating after the cold plunge—typically about 1.5 minutes—relative to nonsmokers. The researchers conclude that some ingredient in cigarette smoke has a long-term vessel-constricting effect.

Nicotine’s effect did show up in the tests, says Lee, who is now at Harvard Medical School in Boston. Dilating blood vessels opened somewhat less when a smoker wore the patch.

The combination of delayed and reduced vessel dilation can translate into cold feet and hands. The effect could be worse than uncomfortable, moreover, because it could allow frostbite to set in more quickly, Lee adds.