Cigarette Smoke Inhibits Contractile Responses of Rat Isolated Colon to Angiotensin II

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Abstract
The contractile response of isolated superfused rat colons to angiotensin II was inhibited almost totally when cigarette smoke was in contact with the serosal surface of the colon. Filtration of visible particles from the smoke diminished but did not abolish this inhibitory action. An inhibitory factor was also retained by the filter papers. One inhibitor, which was dissolved in Krebs buffer, behaved like nicotine. Carbon monoxide and dioxide were effective inhibitors but only at higher concentrations than they are present in cigarette smoke. Removal of carbon dioxide from cigarette smoke did not abolish the inhibitory action. Neither of the gases nor nicotine alone could fully mimic the action of cigarette smoke. It is possible that the inhibitory action of cigarette smoke was due to combined action of these compounds. It is, however, also possible, that cigarette smoke contains still other inhibitory compounds. Cigarette smoke probably had its effect directly on the smooth muscle cells, but activation of inhibitory nerves could not be excluded.