Methanol in combination with nicotine can be harmful for the lungs, making the receptors in the lungs less sensitive.
Senior author Gerard Ahern, an associate professor of pharmacology at Georgetown University Medical Center (GUMC), said that in addition to desensitizing the receptors in the lung and airways, menthol appears to slow or prevent the recovery of sensitivity after the first insult, likely placing the receptors in a desensitized state.
Study co-author, Kenneth Kellar, a professor of pharmacology at GUMC, said that these receptors were also found in the brain, but they did not know yet what effect menthol had on those receptors, or whether they contribute, in any way, to nicotine addiction.
Ahern and his colleague say their study provides a better understanding of how menthol affects the function of the a34 receptor, one of the most prevalent nicotinic acetylcholine receptors expressed in the peripheral nervous system. These receptors are expressed in airway sensory nerves as well as other neurons.
Ahern added that the issue may be that menthol in the presence of nicotine may reduce the irritation enough that a smoker can inhale more deeply, bringing not just nicotine but toxic smoke products farther into the lungs.