Gw. He et Cq. Yang, Comparative study on calcium channel antagonists in the human radial artery: Clinical implications, J THOR SURG, 119(1), 2000, pp. 94-100
Citations number
21
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Objectives: The radial artery is spastic, and calcium channel antagonists h
ave been used clinically in the radial artery for their antispastic effects
. To choose a proper calcium channel antagonist for such a purpose, we comp
ared the in vitro antispastic effects of 4 clinically used calcium channel
antagonists (nicardipine, nifedipine, verapamil, and diltiazem) in the huma
n radial artery. Methods: Radial artery segments taken from patients underg
oing coronary bypass operations were studied in the organ bath. The relaxat
ion by the calcium channel antagonists was compared in the potassium-precon
tracted (25 mmol/L) radial artery. The inhibitory effect of the calcium cha
nnel antagonists at the clinically relevant plasma concentration and a high
er concentration was also studied for the calcium channel antagonists. Resu
lts: All calcium channel antagonists induced a full relaxation (97.8%-100%,
n = 5-7 for each), with higher sensitivity (P =.005, analysis of variance
[ANOVA] among the calcium channel antagonists for the effective concentrati
on of the constrictor [or dilator] agent that caused 50% of maximal contrac
tion [or relaxation]) to nifedipine (-7.37 +/- 0.20 log(10) M) than nicardi
pine (-6.43 +/- 0.39 log(10) M, P =.1), verapamil(-6.08 +/- 0.13 log(10) M,
P =.03), and diltiazem (-5.87 +/- 0.07 log(10) M, P =.01). Pretreatment wi
th the plasma concentration of the calcium channel antagonists (60 nmol/L f
or diltiazem and 20 nmol/L for the others) inhibited the potassium-induced
contraction (n = 6 for each) by nicardipine (from 138.6% +/- 5.8% to 101.4%
+/- 7.6%, P =.001) and nifedipine (to 87.7% +/- 6.8%, P =.0003) but not by
verapamil (to 140.3% +/- 15.2%, P =.9) or diltiazem (to 132.8% +/- 7.3%, P
=.8), although at higher contractions (-4.5 log(10) M) all 4 calcium chann
el antagonists abolished the contraction. Conclusions: Although all calcium
channel antagonists have antispastic effects in the radial artery, the ves
sel has different sensitivities to them. Dihydropyridine derivatives may be
the most potent calcium channel antiagonists and therefore are recommended
for the clinical use for this purpose.