Human urotensin II in internal mammary and radial arteries of patients undergoing coronary surgery.
OBJECTIVE
Internal mammary (IMA) and radial artery (RA) have different incidence of vasospasm and long-term patency rates in arterial grafting. We compared the vasoreactivity of human urotensin II (hU-II) and its receptor with mechanism investigations in IMA and RA.


METHODS
IMA and RA taken from patients undergoing coronary bypass surgery were studied in organ baths. Urotensin receptor expression was determined by RT-PCR.


RESULTS
hU-II contracted IMA with pD(2) of 8.57+/-0.41 and 45.4+/-9.1% E(max) of contraction to 100 mM KCl, whereas caused less contractile responses in RA (pD(2):8.30+/-0.79, E(max):20.4+/-4.8%, p<0.05). Nifedipine inhibited hU-II-contraction in IMA. In U(46619)-precontraction, hU-II elicited comparable relaxation in IMA (pD(2):8.39+/-0.43, E(max):56.1+/-4.0%) and RA (pD(2):9.03+/-0.46, E(max):65.2+/-7.1%). The relaxation was abolished by endothelium denudation and by indomethacin, oxadiazoloquinoxalinone or N(omega)-nitro-L-arginine, oxyhemoglobin, and Ca2+-activated K+ channel (K(Ca)) blockers. Urotensin receptor mRNA was detected in both arteries.


CONCLUSIONS
hU-II is an important spasmogen in arterial grafts with receptors expressed in IMA and RA. hU-II elicits stronger contraction in IMA than in RA and a moderate endothelium-dependent relaxation attributable to nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor with involvement of K(Ca) activation. The relaxant response of endothelium-intact IMA and RA to hU-II demonstrates the importance of preservation of endothelium in these grafts.
Chen
Zhi-Wu
ZW
Providence Heart and Vascular Institute, Starr Academic Center for Cardiac Surgery, and Department of Surgery, Oregon Health & Science University, Portland, OR, USA.
Yang
Qin
Q
Huang
Yu
Y
Fan
Li
L
Li
Xian-Wu
XW
He
Guo-Wei
GW
D000368:Aged; D001026:Coronary Artery Bypass; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects* / Q000378:metabolism; D008875:Middle Aged; D036361:Peptide Hormones / Q000378:metabolism / Q000494:pharmacology*; D017534:Radial Artery / Q000187:drug effects* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
D047908:Intracellular Signaling Peptides and Proteins; D036361:Peptide Hormones; D043562:Receptors, G-Protein-Coupled; C479080:UTS2B protein, human; C121697:UTS2R protein, human