Background: Vasoconstrictor-induced reduction in arterial graft diameter can cause significant flow deprivation. The
aim of this study was to evaluate the effect of vasodilator pretreatment on vasoconstrictor-induced blood vessel
spasm in vitro. Material and Method: Rabbit brachial arteries (BA) and celiac arteries (CA) were cut into rings (3
∼4 mm) and suspended with a force displacement transducer (TSD 125CⓇ, Biopac Inc. USA) in a tissue bath fil-
led with 5 mL modified Krebs solution bubbled with 5% CO2 and 95% O2 at 38
o
C. The rings were contracted
with vasoconstrictors, and the developed tension changes were considered control values. The rings were then pre-
treated with 30μM nitroglycerin, nicardipine, verapamil, and papaverine, respectively, for 40 minutes and rinsed
with the physiologic buffered salt solution three times every 15 min. The vasoconstrictor-induced tension changes
after the previous procedure were considered experimental values. Data are expressed as the percentage tension
induced by vasoconstrictors before and after pretreatment with vasodilators. Result: Nicardipine depressed vaso-
constriction induced by norepinephrine, angiotensin II (AII), and U46619 in both the BA and the CA more sig-
nificantly than did nitroglycerin (p<0.01) and verapamil (p<0.05). Verapamil depressed vasoconstriction induced by
5-hydroxytryptamine (5HT), AII, and U46619 in the BA and by 5HT in the CA more significantly than did nitro-
glycerin (p<0.01). Conclusion: These findings suggest that both nicardipine and verapamil effectively depressed
vasoconstrictor action. Nicardipine is thought to be more effective than verapamil for the prevention of vaso-
constrictor action