EXPOSING YOUNG GUINEA-PIGS TO SIDESTREAM TOBACCO-SMOKE DECREASES RAPIDLY ADAPTING RECEPTOR RESPONSIVENESS

We exposed 21 young guinea pigs to 5 wk of either sidestream tobacco smoke (SS) or filtered air (FA). The exposure started on day 8 of life and ended at 41-45 days of life. The animals were then anesthetized, and lung rapidly adapting receptor (RAR) and slowly adapting receptor (SAR) activities and peak tracheal pressure (TP) were examined in response to mainstream smoke. SS exposure did not alter baseline RAR activity. Low-nicotine smoke increased RAR activity in the FA but not in the SS group. High-nicotine smoke increased RAR activity in both groups but more so in the FA than in the SS group. Baseline TP was lower in the SS group. Both low- and high-nicotine smoke increased TP but more so in the FA than in the SS group. The increase in RAR activity preceded the increase in TP. SS exposure increased baseline SAR activity but did not affect the variable responses of SARs to low- and high-nicotine smoke. We suggest that exposing guinea pigs to SS during development diminishes the responsiveness of RARs to acute inhalation of mainstream smoke.