Korean J Physiol Pharmacol.
1999 Dec;3(6):587-595.
Effects of calcium channel blockers on porcine cardiac and coronary arterial function in ischemia-reperfusion
- Affiliations
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- 1Department of Pharmacology, Chonnam University Medical School, Kwangju, Korea.
- 2Research Institute of Medical Sciences, Chonnam University Medical School, Kwangju, Korea.
- 3Department of Pharmacology, College of Medicine Chosun University, Kwangju 501-191, Korea.
Abstract
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This study was designed to investigate effects of calcium antagonists
on endothelial and neuronal dysfunction of right coronary artery (RCA)
induced by ischemia- reperfusion in anesthetized, open-chest pigs.
After reperfusion, pigs were sacrificed and the RCA was rapidly
dissected for in vitro experiments. Experimental groups were divided
into 4 groups: control (C-RCA), ischemia-reperfusion only (I-RCA),
verapamil infusion (VI-RCA) and nifedipine infusion (NI-RCA) group,
respectively. The ischemia did not affect hemodynamics, mean arterial
pressure, heart rate, LVdP/dtmax, and decreased RCA flow. Arterial
pressure and heart rate during ischemia-reperfusion were decreased in
VI-RCA and NI-RCA, and RCA flow during reperfusion was increased in
NI-RCA. 5-Hydroxytryptamine (5-HT) produced concentration-dependent
contractions in C-RCA. The 5-HT-induced contractions were potentiated
in I-RCA and VI-RCA, but not in NI-RCA. Endothelium-dependent
relaxation by calcium ionophore A23187 was inhibited in I-RCA and
VI-RCA, and recovered in NI-RCA. Cyclic GMP contents were decreased in
I-RCA group alone. Electrical field stimulation in C-RCA produced
transient and frequency-dependent contractions and at 50 Hz caused
biphasic contractions. The transient contractions were not affected by
pretreatment with phentolamine and atropine, but the biphasic
contraction was altered by the pretreatment. Both contractions were
inhibited in I-RCA, and were partially recovered in VI-RCA and NI-RCA.
Ischemia-reperfusion of RCA in pigs causes endothelial and neuronal
dysfunctions, and calcium antagonists partially prevent both.