More clues to smoking-SIDS link

Last updated: Wednesday, February 13, 2008 Print

The known increase in the risk of a baby succumbing to sudden infant death syndrome, or SIDS, when the mother smokes during pregnancy may be due specifically to the effect of nicotine, Canadian researchers report.

Normally, a drop in oxygen in the bloodstream arouses a baby from sleep, which leads to better breathing. During the newborn period, this is triggered by specialised cells in the adrenal gland that detect oxygen deprivation and respond by releasing catecholamines - hormones such as adrenaline that have a generally stimulating effect.

The current study, using rats, shows that nicotine exposure impairs the ability of these so-called chromaffin cells to release catecholamines.

Catecholamine release by adrenal chromaffin cells in response to low oxygen or high carbon dioxide is critical for infants to adapt to life outside of the womb, principal investigator Dr Colin A. Nurse and colleagues point out in the Federation of American Societies for Experimental Biology (FASEB) Journal.

How the study was done
The team, at McMaster University in Hamilton, Ontario, conducted several experiments to assess chromaffin cell responses in newborn rats when the mothers were given either saline or nicotine 14 days before mating and during pregnancy.

The investigators found that nicotine caused a marked suppression or loss of sensitivity to low oxygen in chromaffin cells from the offspring. Sensitivity to high carbon dioxide, on the hand, seemed normal.

Nurse and colleagues conclude that maternal smoking impairs the ability of newborn offspring to respond to oxygen deprivation, through the direct action of nicotine. – (ReutersHealth) -(February 2008)

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