Journal of Applied Physiology, Vol 51, Issue 3 693-698, Copyright © 1981 by American Physiological Society
Effects of 5-hydroxytryptamine on neuroeffector junction in human pulmonary artery
W. K. Freeman, D. K. Rorie and G. M. Tyce
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 intra-parenchymal 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.
