[Interspecies differences in the reactivity of smooth tracheobronchial muscles].

There are considerable differences in the reactivity of tracheobronchial muscles to bronchoconstricting substances in guinea pigs and rats. The aim of the present investigation was to assess whether these functional differences have a morphological or biochemical background. Therefore specimens of this tissue were taken for histological and biochemical examination i. e. assessment of cyclic nucleotides. While in the nucleotide content no interspecific differences were found, there were some morphological differences which may explain the less marked response of smooth muscles of the rat to bronchoconstricting stimuli.