Y. Chijiiwa et al., DIRECT INHIBITORY EFFECT OF NEUROTENSIN ON ISOLATED GASTRIC SMOOTH-MUSCLE CELLS OF GUINEA-PIG VIA THE CYCLIC-GMP SYSTEM, Digestion, 54(3), 1993, pp. 135-138
Smooth muscle cells isolated from the gastric muscle layers of the gui
nea pig were used to determine whether neurotensin can inhibit the con
tractile response produced by 10(-6) M carbachol by exerting a direct
action on muscle cells. In addition, the inhibitory effect of 2',5'-di
deoxyadenosine, an inhibitor of adenylate cyclase, and methylene blue,
an inhibitor of guanylate cyclase, on the neurotensin-induced relaxat
ion of gastric smooth muscle cells were examined. Neurotensin inhibite
d the contractile response produced by carbachol in a dose-dependent m
anner, with an IC50 value of 5 nM. 2',5'-Dideoxyadenosine did not have
any significant effect on the neurotensin-induced relaxation. On the
other hand, methylene blue significantly inhibited the relaxation prod
uced by neurotensin. These results strongly suggest that the action of
neurotensin is mediated by cyclic GMP.