Ro. Salonen et al., A NEW GUINEA-PIG MODEL FOR ACUTE INHALATION STUDIES ON COMBINED EFFECTS OF COLD-AIR AND POLLUTANTS, Respiration physiology, 113(3), 1998, pp. 271-283
We have developed a new small animal model for acute inhalation studie
s on combined effects of cold air and gaseous urban air pollutants. Th
e anaesthetised, tracheostomised and paralysed guinea-pig was placed i
nside a small, sealed whole-body-box, in which it was ventilated mecha
nically by using cyclic negative pressure (P-box) for active expansion
of the chest. During a 2-h normal ventilation with warm humid air (n
= 6), there was a need for increasing P-box with time to maintain the
fixed tidal volume (V-T) of 11 ml/kg. No such need was seen in the exp
eriments with 15-min periods of isocapnic hyperventilation at 80 and 1
20 breaths/min (n = 13). During the 2-h normal ventilation and in expe
riments with hyperventilation, there was a gradual increase in heart r
ate and small gradual decreases in Pa-CO2 and pH with time. Cold air SO2 2.5 ppm produced a significantly stronger bronchoconstriction (De
lta V-T = - 30.3 +/- 7.2%, n = 6, P < 0.05) than clean cold dry air (D
elta V-T = - 10.6 +/- 1.3%, n = 6) and cold air + NO2 2.5 ppm (Delta V
-T = - 13.2 +/- 3.3%, n = 6), although these three exposure conditions
produced similar decreases in tracheal air and retrotracheal tissue t
emperatures. With the present guinea-pig model, the combined respirato
ry effects of cold air and gaseous urban air pollutants can be investi
gated in a highly controlled manner. (C) 1998 Elsevier Science B.V. Al
l rights reserved.