|MadSci Network: Biochemistry|
I couldn't find any studies that directly measured the effect of cigarette smoke on the digestion of starch by amylase. I could find a few studies on the effects of cigarette smoking or the effects of nicotine on salivary amylase activity or levels (see below). Also, I found a report on the effect of nicotine on the release of amylase by the pancreas (see below). Before I discuss these studies, I want to provide a little background about starch digestion by amylase.
You are correct that starch, a polysaccharide, is digested by amylase. In the saliva, starch is broken down by salivary alpha-amylase (also called ptyalin) which is made in the salivary glands. Once the food and saliva are swallowed and enter the stomach, the low pH of the stomach inactivates the alpha-amylase. When the food enters the small intestine it is exposed to pancreatic alpha-amylase. Both the salivary and pancreatic alpha-amylase catalyze the same reaction, leading to the formation of oligosaccharides (reference 1)
I found two studies (referencse 2 and 3) that found that the amount of amylase activity in the saliva of people who smoke cigarettes was not significantly different from that present in the saliva of non-smokers. Another study (reference 4) found that acute administration of nicotine to non-smokers was associated with increased salivary amylase activity and protein levels. Nicotine has been found to significantly decrease the release of amylase from pancreatic cells (acini) in response to hormones (insulin and cholecystokinin) and to significantly increase the amount of amylase present in the cells (reference 5). The authors of this last study propose that these effects of nicotine may account for the increased incidence of pancreatitis and pancreatic cancer in people who smoke cigarettes.
For more information on the dangers of cigarette smoking, please see these web pages:
1 Digestion and Absorption. (Chapter 25) In Review of Medical Physiology, 16th edition. Edited by William F. Ganong. Appleton & Lange. 1993
2 Nagaya, T. and Okuno, M. (1993) No effect of smoking or drinking habits on salivary amylase. Toxicology Letters. volume 66 (#3) pp. 257-261
3 Kivela, J. et al. (1997) Salivary carbonic anhydrase VI concentration and its relation to basic characteristics of saliva in young men. Acta Physiologica Scandinavica. volume 161 (#2) pp. 221-225
4 Maier, H. et al. (1991) Effects of acute nicotine application on the function of the human parotid gland. Laryngo-Rhino-Otologie. vloume 70 (#1) pp. 24-26
5 Chowdhury, P. et al. (1995) Structural and functional changes of rat exocrine pancreas exposed to nicotine. International Journal of Pancreatology. Volume 18 (#3) pp. 257-264
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