TY - JOUR
T1 - 5-Hydroxytryptamine inhibits pressor responses to preganglionic sympathetic nerve stimulation in pithed rats
AU - Villalón, Carlos M.
AU - Contreras, Judith
AU - Ramírez-San Juan, Eduardo
AU - Castillo, Carlos
AU - Perusquía, Mercedes
AU - López-Muñoz, Francisco J.
AU - Terrón, JoséA A.
PY - 1995/7/14
Y1 - 1995/7/14
N2 - 5-Hydroxytryptamine (5-HT) inhibits contractile responses to adrenergic nerve stimulation in several blood vessels and organs. We have now investigated the potential ability of 5-HT to inhibit the presser responses caused by preganglionic sympathetic stimulation (T7-T9) in pithed rats. Sympathetic stimulation (0.03, 0.1, 0.3, 1 and 3 Hz) resulted in frequency-dependent increases in diastolic blood pressure; these effects were augmented after i.v. treatment with desipramine (50 μg/kg). During continuous infusions of 5-HT (1.8, 3.1, 5.6 and 10 μg/kg.Min, I.v.), but not of saline, the pressor responses were dose-dependently inhibited in both control and desipramine-pretreated rats; this inhibitory effect of 5-HT was significantly more pronounced at lower frequencies of stimulation. In contrast, the above infusions of 5-HT did not inhibit the pressor responses induced by i.v. bolus injections of exogenous norepinephrine (up to 3 μg/kg). Taken together, the above findings suggest an operative 5-HT-induced prejunctional inhibition of sympathetic nerve activity on the systemic vasculature in vivo.
AB - 5-Hydroxytryptamine (5-HT) inhibits contractile responses to adrenergic nerve stimulation in several blood vessels and organs. We have now investigated the potential ability of 5-HT to inhibit the presser responses caused by preganglionic sympathetic stimulation (T7-T9) in pithed rats. Sympathetic stimulation (0.03, 0.1, 0.3, 1 and 3 Hz) resulted in frequency-dependent increases in diastolic blood pressure; these effects were augmented after i.v. treatment with desipramine (50 μg/kg). During continuous infusions of 5-HT (1.8, 3.1, 5.6 and 10 μg/kg.Min, I.v.), but not of saline, the pressor responses were dose-dependently inhibited in both control and desipramine-pretreated rats; this inhibitory effect of 5-HT was significantly more pronounced at lower frequencies of stimulation. In contrast, the above infusions of 5-HT did not inhibit the pressor responses induced by i.v. bolus injections of exogenous norepinephrine (up to 3 μg/kg). Taken together, the above findings suggest an operative 5-HT-induced prejunctional inhibition of sympathetic nerve activity on the systemic vasculature in vivo.
KW - 5-hydroxytryptamine
KW - blood vessels
KW - prejunctional inhibition
KW - sympathetic outflow
UR - http://www.scopus.com/inward/record.url?scp=0029119366&partnerID=8YFLogxK
U2 - 10.1016/0024-3205(95)02008-7
DO - 10.1016/0024-3205(95)02008-7
M3 - Artículo
SN - 0024-3205
VL - 57
SP - 803
EP - 812
JO - Life Sciences
JF - Life Sciences
IS - 8
ER -