The effects of 5-hydroxytryptamine on release of norepinephrine and on contraction of smooth muscle in human pulmonary artery were studied. Helical strips were prepared from intraparenchymal arteries removed 3-18 h after death. The strips were labeled with L-[7-3H]norepinephrine and mounted for superfusion and isometric tension recording. Electrical stimulation (10 V, 2 ms, 2 Hz) of the strips increased the release of total radioactivity; this release was blocked by tetrodotoxin. 5-Hydroxytryptamine (10-5 M) exerted a cocaine-sensitive, indirect sympathomimetic effect on the overflow of norepinephrine from resting strips. This action was not blocked by methysergide. No effect of 5-hydroxytryptamine on release of norepinephrine from electrically stimulated tissue could be demonstrated. 5-Hydroxytryptamine (10-5 M) also caused contractions of pulmonary smooth muscle, not blocked by phentolamine (10-5 M) but mediated in part through methysergide-sensitive 5-hydroxytryptamine receptors.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Applied Physiology Respiratory Environmental and Exercise Physiology|
|State||Published - Jan 1 1981|
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