Effects of neurotensin in feline pial arteries, guinea-pig ileum and portal vein of rat and guinea-pig.

The effect of neurotensin (NT) was investigated in several vascular and intestinal smooth muscle preparations. No effect of NT (6 X 10(-12)-6 X 10(-5) M) was detected in feline pial arteries in situ employing perivascular microapplication and TV-image splitting for the measurement of vascular diameter. In vitro, the effect of NT was derived from recordings of isometric contraction. NT (10(-10)-10(-5) M) did not influence basal tension, frequency and peak phasic contraction of the whole guinea-pig portal vein (GPV) or its longitudinal strip (GLSPV). Intact reactivity of these preparations was derived from the contraction induced by carbamoylcholine or norepinephrine. In contrast, NT (6 X 10(-10)-6 X 10(-6) M) increased basal tension, frequency, and peak phasic contraction of the longitudinal strip of rat portal vein (RLSPV). Furthermore, NT induced a dose-dependent contraction in the terminal ileum of the guinea-pig (GTI) which was preceded by a transient relaxation. Comparing the effects obtained in GPV and GTI or found in RLSPV and GLSPV it is evident that the variable effects of NT depend on the location of smooth muscle and on animal species, respectively.