AJP - Gastrointestinal and Liver Physiology, Vol 243, Issue 5 404-G409, Copyright © 1982 by American Physiological Society
Effect of neurotensin on mechanical and intracellular electrical activity of the canine stomach
K. M. Sanders, P. Schmalz and J. H. Szurszewski
Intracellular microelectrode and standard organ bath techniques were used
to study in vitro the effects of neurotensin on the electrical and
mechanical activities of canine antral circular smooth muscle. Neurotensin
reduced or abolished spontaneous contractions. Muscarinic and adrenergic
antagonists and tetrodotoxin did not block the effects of neurotensin,
suggesting that the action of neurotensin was due to a direct action on the
smooth muscle cell. Although the inhibitory effect of norepinephrine and
neurotensin was similar, the effect of neurotensin did not appear to occur
by an adrenergic mechanism because alpha- and beta-receptor blockade had no
effect. Neurotensin also reduced or abolished contractions stimulated by
pentagastrin and acetylcholine. The inhibitory effect of neurotensin on
spontaneous acetylcholine- and pentagastrin-stimulated contractions was
associated with a decrease in the amplitude and duration of the plateau
potential of the gastric action potential. The data suggest that modulation
of antral contractions by neurotensin occurs through a voltage-dependent
mechanism that operates during the plateau potential.
