Analysis of vasoreactivity of isolated human radial artery.
Radial artery (RA) is increasingly used as graft for coronary artery bypass grafting due to its good long-term patency. However, the mechanism of peri- and post-operative spasm is still unclear. Because of that, the aim of our study is to analyze the contractility of RA and to determine whether the presence of functional endothelium alters its contractile properties. Contractions of isolated RA rings were provoked by exogenously applied vasoconstrictors or by electrical field stimulation (EFS, 20 Hz). The order of vasoconstrictors potency based on their EC50 values was as follows: angiotensin II > phenylephrine > 5-hydroxytriptamine. Presence of endothelium increased both EC50 and maximal contraction to phenylephrine and angiotensin II, but inhibited reactivity of RA to 5-hydroxytriptamine. Spontaneous rhythmic contractions (SRC, <4 mHz) and EFS-induced contractions of RA are endothelium-independent and weaker than contractions induced by exogenously applied vasoconstrictors. Our study concludes that RA shows marked sensitivity and reactivity to angiotensin II, phenylephrine, and 5-hydroxytriptamine. Further investigations are necessary to answer why angiotensin II and phenylepehrine induce stronger contractions in the presence of endothelium. In addition, SRC as well as contractions of neurogenic origin may take part in developing vascular spasm of RA.
Stojnic
Natasa
N
Departement of Clinical Pharmacology, Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, Serbia and Montenegro.
Bukarica
Ljiljana Gojkovic
LG
Peric
Miodrag
M
Bumbasirevic
Marko
M
Lesic
Aleksandar
A
Lipkovski
Jasmina Markovic
JM
Heinle
Helmut
H
D000804:Angiotensin II / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology; D017534:Radial Artery / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology; D013997:Time Factors; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D010656:Phenylephrine; D012701:Serotonin