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

Abstract

Abstracr:The contractile response of isolated superfused rat colons to angiotensinII 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 ofcigarette 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.

Cigarette Smoke Inhibits Contractile Responses of Isolated Hamster Stomach Strip to Prostaglandin E2

“…This supports our earlier conclusion that cigarette smoke contains a smooth muscle inhibitor different from nicotine (Toivonen et al 1981). We also concluded that the inhibitor of rat colons which was dissolved in the buffer solution could be nicotine (Toivonen et al 1981). It is in agreement with the present findings, because the smoke treated buffer solutions did not inhibit the responses of hamster stomach strips to PGE2.…”

“…The main stream smoke from one lighted cigarette was introduced into the middle of the tissue jacket in about 3 min. (Toivonen et al 1981). Between the smoke exposures a continuous air flow of about I I/min.…”

“…The contractile responses were expressed as per cent of the agonist amount which was injected during the exposure to give the same response in normal conditions immediately before the exposure (see Toivonen et a/. 1981 During cigarette smoke exposure for 3 min.…”

“…1980). Cigarette smoke inhibited rat colons in similar exposure arrangements even more strongly than nicotine (Toivonen et a/. 1981).…”

“…It was suggested that the inhibitory action of smoke could be due t o the combination of nicotine and carbon monoxide and possibly also to carbon dioxide. The presence of other inhibitory compounds was, however, not excluded (Toivonen et al 1981).…”