Ca2+ handling mechanisms underlying neuropeptide Y-induced contraction in canine basilar artery.
The effects of neuropeptide Y on isometric tension simultaneously measured with cytosolic Ca2+ concentration ([Ca2+]cyt) and Ca2+ sensitivity of contractile elements were studied in isolated canine basilar arteries. Neuropeptide Y (1-100 nM) increased [Ca2+]cyt and tension in a concentration-dependent and parallel manner, whereas 9,11-dideoxy-11 alpha,9 alpha-epoxymethano prostaglandin F2 alpha (U46619) (10-100 nM), a thromboxane A2 mimetic, produced a large contraction with a small increase in [Ca2+]cyt. Ca2+ channel antagonists such as d-cis-diltiazem (10 mM) abolished both [Ca2+]cyt and tension augmented by neuropeptide Y. In Ca(2+)-free solution containing 0.2 mM EGTA, neuropeptide Y did not change [Ca2+]cyt and tension, whereas U46619 transiently increased both of them. Furthermore, neuropeptide Y apparently did not affect the Ca2+ sensitivity when assessed in the artery permeabilized with Staphylococcus aureus alpha-toxin, whereas U46619 augmented it. These findings suggest that neuropeptide Y-induced contraction in the canine basilar artery is produced mainly by Ca2+ influx through L-type Ca2+ channels.
Tanaka
Y
Y
Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Nakazawa
T
T
Ishiro
H
H
Saito
M
M
Uneyama
H
H
Iwata
S
S
Ishii
K
K
Nakayama
K
K
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D001488:Basilar Artery / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009478:Neuropeptide Y / Q000502:physiology*; D010539:Permeability; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D009478:Neuropeptide Y; D011450:Prostaglandin Endoperoxides, Synthetic; D014662:Vasoconstrictor Agents; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D002118:Calcium