Browsing by Author "Racchi, H"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Adenosine 5′-triphosphate and neuropeptide Y are co-transmitters in conjunction with noradrenaline in the human saphenous vein
    (1999) Racchi, H; Irarrázabal, MJ; Howard, M; Morán, S; Zalaquett, R; Huidobro-Toro, JP
    1 Human saphenous veins were used to assess the cooperative participation of adenosine 5-triphosphate (ATP), neuropeptide Y (NPY), and noradrenaline (NA) in the vasomotor responses elicited following electrical depolarization of the perivascular nerve terminals. Rings from recently dissected human biopsies were mounted to record isometric muscular contractions; the motor activity elicited in the circular muscle layer following electrical depolarization (2.5-20 Hz, 50 V, 0.5 msec) were recorded.
  • No Thumbnail Available
    Item
    Neuropeptide Y Y-1 receptors are involved in the vasoconstriction caused by human sympathetic nerve stimulation
    (1997) Racchi, H; Schliem, AJ; Donoso, MV; Rahmer, A; Zuniga, A; Guzman, S; Rudolf, K; HuidobroToro, JP
    Neuropeptide Y, a novel neurotransmitter, interacts with selective membrane receptors to cause vasoconstriction. Frequency- and concentration-dependent isometric contractions were observed in human inferior mesenteric artery and vein mounted rings that were stimulated with either electrical pulses (70 V, 0.5 ms, 2.5-20 Hz) or noradrenaline. The antagonism elicited by 100 nM tetrodotoxin and 1 mu M guanethidine confirmed the neuronal and sympathetic origins of the vasomotor response. Incubation with BIBP 3226 ((R)-N-2-(diphrnacetyl)-N-(4-hydroxyphenyl)-methyl-D-arginineamide), a selective neuropeptide Y Y, receptor antagonist, significantly reduced the vasoconstriction. The incomplete antagonist activity of BIBP 3226 tends to support the hypothesis of sympathetic co-transmission involving neuropeptide Y, adenosine 5'-triphosphate and noradrenaline. These findings were confirmed in parallel studies using rat superior mesenteric artery and vein ring preparations. (C) 1997 Elsevier Science B.V.