Watanabe H, Furukawa Y, Iwatsuki K, Chiba S
Jpn J Pharmacol. 1981 Oct;31(5):725-30. doi: 10.1254/jjp.31.725.
Effects of nicardipine, a newly synthesized dihydropyridine vasodilator exhibiting cyclic phosphodiesterase inhibitory properties, were studied in the isolated canine atrium which was cross-perfused with blood from a donor dog. When nicardipine (1.0-10 micrograms/kg) was administered intravenously to the donor dogs, the systemic blood pressure decreased and the heart rate did not significantly change. However, the contraction and beat rate of the isolated atrium were only slightly decreased. At larger doses (30-100 micrograms/kg, i.v.), the systemic blood pressure fell markedly and was usually accompanied by marked bradycardia, which was greater than that of the isolated atrium. Nicardipine injected into the sinus node artery of the isolated atrium caused dose-related negative chronotropic and inotropic effects which were less pronounced than those of verapamil. In contrast, papaverine increased right atrial rate and contractile force. Nicardipine similarly to verapamil and unlike manganese ion caused greater inhibition of the right atrial contraction at higher than lower pacing frequencies. From these results, it is concluded that nicardipine may produce predominantly cardiac depressant properties as a calcium antagonistic, and that such may not be related to phosphodiesterase inhibition in cardiac tissues.
尼卡地平是一种新合成的具有环磷酸二酯酶抑制特性的二氢吡啶类血管扩张剂，本研究在从供血犬交叉灌注血液的离体犬心房中对其作用进行了研究。当向供血犬静脉注射尼卡地平（1.0 - 10微克/千克）时，体循环血压下降，心率无显著变化。然而，离体心房的收缩和搏动频率仅略有下降。在较大剂量（30 - 100微克/千克，静脉注射）时，体循环血压显著下降，且通常伴有明显的心动过缓，该心动过缓程度大于离体心房。向离体心房的窦房结动脉注射尼卡地平会引起剂量相关的负性变时和变力作用，但其作用不如维拉帕米明显。相比之下，罂粟碱可增加右心房率和收缩力。与维拉帕米类似，与锰离子不同，尼卡地平在较高起搏频率下比在较低起搏频率下对右心房收缩的抑制作用更强。从这些结果可以得出结论，尼卡地平作为一种钙拮抗剂可能主要产生心脏抑制特性，且这种特性可能与心脏组织中的磷酸二酯酶抑制无关。
