Abstract 2101 Poster Session IV, Tuesday, 5/4 (poster 181)

We have found that prenatal nicotine exposure has effects on breathing patterns compatible with a decreased compliance and/or increased airway resistance, i.e., a decreased in tidal volume and an increase in respiratory rate and effective impedance. Our hypothesis was that the effects of prenatal nicotine exposure would persist beyond the discontinuation of exposure and would not be worsened by postnatal exposure.

Subjects: Prenatal nicotine exposure alone(PRE): 9 lambs (40 mg·d-1 sc. given to ewe during the last third of gestation). Postnatal nicotine exposure alone (POST): 7 lambs (2 mg·kg-1 sc. given only from birth). Pre- and postnatal exposure combined (P&P): 7 lambs (pre- and postnatal treatment combined. Controls (C): 11 unexposed lambs.

Methods: Lambs were studied during wakefulness at a mean age of 4 to 5 d using a combined pneumotachometer and airway occlusion pressure device (Eur J appl Physiol 74:44, 1996). Minute ventilation (V1, ml·kg-1·min-1), tidal volume (VT, ml·kg-1), respiratory rate (min-1), airway occlusion pressures (P0.1, cmH2O), end tidal PCO2 (PETCO2, %), mean inspiratory flow (VT/TI, ml·s-1) and effective impedance (P0.1/(VT/TI), cmH2O·ml-1·s) were measured breath-by-breath.

Results: Cotinine levels in the ewes were (18±5 ng·ml-1, mean ±SD) and in postnatally treated lambs (132±66 ng·ml-1). Results are presented in the table

Table 1 No caption available
Full size table

Conclusions: The PRE group had the most marked alterations in breathing patterns and these effects were not worsened by further postnatal exposure. The POST group showed only a slight elevation of effective impedance. These findings are compatible with the hypothesis of a nicotine-induced altered fetal lung development. The observed findings suggest, furthermore, that prenatal nicotine exposure alone may produce effects commonly ascribed to the irritant effects of tobacco smoke. (HD 28916)