Smoking Research Today is a free monthly online journal that collates and summarizes the latest research about Smoking, including details on cigarettes, cancer, lung, tar, nicotine.

Respiratory control in neonatal rats exposed to prenatal cigarette smoke.

Pendlebury JD, Wilson RJ, Bano S, Lumb KJ, Schneider JM, Hasan SU

Department of Pediatrics, Institute of Maternal and Child Health, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.

RATIONALE: Prenatal cigarette smoke (CS) exposure, increased environmental temperature, and hypoxic episodes have been postulated as major risk factors for sudden infant death syndrome. OBJECTIVES: To test the hypothesis that maternal CS exposure disrupts eupneic breathing and depresses breathing responses of neonatal rats to thermal and hypoxic challenges. METHODS: Experiments were performed on 1-week-old rat pups exposed prenatally to CS (n = 39) or room air (sham; n = 30). Breathing patterns were recorded by whole-body plethysmography during thermoneutral or hyperthermic states under normoxic and hypoxic conditions. MEASUREMENTS AND MAIN RESULTS: Mean pup weight, breaths per minute, and gasping respiratory patterns were measured for both smoke- and sham-exposed groups during thermoneutral and hyperthermic states under normoxic and hypoxic conditions. Under thermoneutral conditions, hypoxia caused gasping in CS-exposed animals but not in sham-exposed animals. Furthermore, under hyperthermic conditions, whereas hypoxia induced gasping in both groups, only CS-exposed animals exhibited a pronounced and longer lasting respiratory depression after the termination of hypoxia. CONCLUSIONS: We show that prenatal CS exposure increases the likelihood of gasplike respiration and provide the first experimental evidence that the combined effects of prenatal CS exposure and hyperthermia dramatically prolong the time required for neonates to return to eupneic breathing after hypoxia. These observations provide important evidence of how prenatal CS exposure, hypoxic episodes, and hyperthermia might place infants at higher risk for sudden infant death syndrome.

Published 19 May 2008 in Am J Respir Crit Care Med, 177(11): 1255-61.
Full-text of this article is available online (may require subscription).

© 2006-2008 Smoking Research Today. All Rights Reserved.