Aims: Accumulating evidence indicates that coronary vasoconstricting responses are enhanced at the edges of coronary segment implanted with a drug-eluting stent (DES) compared with a bare-metal stent (BMS) in humans. We have recently demonstrated that Rho-kinase pathway plays an important role in DES-induced coronary hyperconstricting responses associated with inflammatory changes in pigs in vivo. This study examined whether long-term treatment with calcium channel blocker suppresses DES-induced coronary hyperconstricting responses in pigs in vivo.
Methods and results: Paclitaxel-eluting stent (PES) and a BMS were randomly implanted in the left coronary arteries in male domestic pigs with and without long-acting nifedipine (NIF, 4 mg/kg/day) for 4 weeks (n = 7 each). Coronary vasomotion was evaluated by quantitative coronary angiography at least 24 h after withdrawal of NIF to avoid its direct effects on coronary vasomotion. In the control group (without NIF), coronary vasoconstricting responses to serotonin (10 and 100 µg/kg, i.c.) were significantly enhanced at the PES site compared with the BMS site (P = 0.009), which were abolished by hydroxyfasudil (90 and 300 µg/kg, i.c.), a selective Rho-kinase inhibitor. The PES-induced vasoconstricting responses were significantly inhibited in the NIF group (P = 0.019). Histological examination showed that inflammatory cell accumulation and microthrombus formation were enhanced at the PES site compared with the BMS site (P < 0.05), both of which were significantly suppressed by NIF associated with reduced Rho-kinase expression and activity (P < 0.05).
Conclusion: These results indicate that long-term treatment with NIF suppresses PES-induced coronary abnormalities partly through Rho-kinase pathway inhibition in vivo.