Species differences in circulatory responses to nasopharyngeal perfusion with smoke

Cardiovascular changes were observed in five species of laboratory mammals during upper airway perfusion with cigarette smoke. Apnoea occurred, both before and after vagotomy, in all species. Blood pressure always went up in rabbits, rats and hamsters but was not much affected in cats and guinea-pigs. Before vagotomy heart rate fell in rabbits and rats, rose in hamsters but did not change in cats and guinea-pigs. Vagotomy affected heart rate changes only in rabbits and rats. Results demonstrate markedly different autonomic responses in different species.