Mechanism of neurotensin-induced pressor effect and tachycardia in guinea pigs

Emerging role of neurotensin in regulation of the cardiovascular system

“…In support of this notion, NT administration is associated with heart rate acceleration in rat (Bachelard et al, 1992;Chahl and Walker, 1981;Rioux et al, 1982a, 1982b), guinea-pig (Bachelard et al, 1985Kerouac et al, 1981;Nisato et al, 1994;Rioux et al, 1982a;Rioux and Lemieux, 1992), and cat (Pokrovsky and Osadchiy, 1995).…”

“…Heart rate acceleration induced by NT upon systemic administration (Kerouac et al, 1981;Rioux et al, 1982a) or following its infusion in isolated, perfused guinea-pig hearts (Bachelard et al, 1985) is not abolished by ganglion blocking agents or antagonists of β-adrenoreceptors, H 2 -histamine and 5-hydroxytryptamine receptors, thus indicating a direct effect of NT on sinoatrial node. Alternatively, NT-induced positive chronotropic responses could be mediated via stimulation of substance P and/or calcitonin generelated peptide release from cardiac primary sensory neurons (Rioux et al, 1988).…”

“…At nanomolar concentrations, it elicits marked hypotensive effects upon intravenous infusion in rat (Chahl and Walker, 1981;Di Paola and Richelson, 1990;Quirion et al, 1980d;Rioux et al, 1982a) and dog (Bauer et al, 1995;Ertl et al, 1993). In contrast, NT produces dose-dependent increase in blood pressure in guinea-pig (Bachelard et al, 1987;Kerouac et al, 1981;Nisato et al, 1994;Rioux et al, 1982a;Rioux and Lemieux, 1992). In many studies, NT has also been reported to evoke biphasic or triphasic variations of blood pressure (Gully et al, 1996;Kaczynska and Szereda-Przestaszewska 2012;Kerouac et al, 1981Kerouac et al, , 1983Nisato et al, 1994;Oishi et al, 1981;Onarheim et al, 1982;Quirion et al, 1980d;Rioux et al, 1982aRioux et al, , 1982b.…”

“…Pressor responses to NT are completely abolished by ganglion blocking agents, reserpine or a mixture of α-and β-adrenoreceptor antagonists, thus indicating the involvement of catecholaminedependent mechanism (Kerouac et al, 1981;Rioux et al, 1982a).…”

Evidence that neurotensin mediates postprandial intestinal hyperemia in the python,Python regius

“…In rats and dogs, systemic administration of NT causes hypotension, increases vascular permeability, and increases intestinal blood flow (5,19,29). NT also leads to tachycardia and increases cardiac contractility (15,20). These findings, together with the elevated levels of circulating levels of NT during digestion (30,35), suggest a role for NT in regulating the postprandial cardiovascular changes.…”