Insulin effects on the sympathetic contraction of rabbit ear arteries.
Electrical field stimulation (4 Hz, 0.2 ms, 70 V supramaximal voltage, 10 s duration) produced contraction of perfused rabbit central ear arteries, and this contraction was reduced by incubation with insulin (0.6--200 mU/ml). This inhibitory effect of insulin was not significantly modified by removing the endothelium, or by treatment with N(W)-nitro-L-arginine (L-NA, 10(-4) M), meclofenamate (10(-5) M), ouabain (10(-6) M), or cocaine (10(-5) M). Insulin (200 mU/ml) did not modify the vascular contraction due to exogenous norepinephrine (10(-8)--10(-4) M) nor the relaxation due to acetylcholine (10(-8)--10(-4) M). This suggests that insulin may reduce vascular contraction by sympathetic stimulation, and this effect is not dependent on endothelial nitric oxide, prostanoids, or Na(+)--K(+) pump activation.
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Arzobispo Morcillo, 2, 28029 Madrid, Spain. angeluis.villalon@uam.es
A L
AL
García-Villalón
N
N
Fernández
L
L
Monge
M A
MA
Martínez
B
B
Gómez
G
G
Diéguez
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004423:Ear / Q000098:blood supply; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D007328:Insulin; D014662:Vasoconstrictor Agents; D000109:Acetylcholine; D009638:Norepinephrine