Characterization of NPY receptors mediating contraction in rat intramyocardial coronary arteries.
In vitro experiments in a microvascular myograph were designed in order to characterize the receptor subtypes and the mechanisms underlying the contractions induced by neuropeptide Y (NPY) in rat coronary small arteries. The rank order of potency for NPY-receptor agonist-induced increases in tension in endothelium-intact preparations was polypeptide Y (PYY)> NPY > or = [Leu31Pro34]NPY, while NPY(13-36) only induced small contractions at the highest concentration applied. The selective neuropeptide Y1 receptor antagonist, BIBP 3226, caused rightward shifts in the concentration-response curves for NPY and the slope of the Schild plot was not significantly different from unity. The pA2 value for BIBP 3226 against NPY was 7.88+/-0.15 (n = 6). We have earlier shown that endothelial cell removal does not change the contractile responses induced by NPY, but indomethacin (3 x 10(-6) M) significantly reduced the contractions induced by the peptide. In contrast, the thromboxane receptor antagonist, SQ29548, which abolished the contractions induced by the thromboxane analogue, U46619, did not change the concentration-response curves for NPY. In conclusion, the present study suggests that Y1 receptors mediate NPY-induced contractions in rat coronary resistance arteries, and that a non-thromboxane prostanoid is involved in the contractile mechanism.
Prieto
D
D
Departamento de Fisiologia, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
García-Sacristán
A
A
Simonsen
U
U
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009478:Neuropeptide Y / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D019894:Peptide YY / Q000494:pharmacology / Q000502:physiology; D011453:Prostaglandins / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017476:Receptors, Neuropeptide Y / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
C092926:BIBP 3226; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D009478:Neuropeptide Y; D011453:Prostaglandins; D017476:Receptors, Neuropeptide Y; D017482:Receptors, Thromboxane; D019894:Peptide YY; C045749:SQ 29548; D001120:Arginine; D007213:Indomethacin