间硝苯啶和美托洛尔在心血管系统中的相互影响

美托洛尔(Met)加强间硝幕啶(m-Nif)对离体豚鼠心房阶梯现象的抑制作用,但不影响休息后加强,m-Nif对氯化钙引起兔肺动脉环收缩的拮抗也被Met加强,两药合用后,拮抗去甲肾上腺素加快豚鼠右心房率的作用比单用稍强,在整体实验,Met加强m-Nif减慢麻醉犬心率。同时减弱m-Nif增加心输出量的作用,结果表明,Met加强m-Nif阻滞细胞外Ca~(2+)内流,加强时心肌和血管平滑肌收缩的抑制,

Interaction between m-nifedipine and metoprolol in cardiovascular system

The combined effects of m-ni fedipine (m-Nif) with metoprolol (Met) on cardiovascular system were studied in vitro and in vivo. Met enhanced the inhibitory effect of m-Nif on the staircase phenomenon in guinea-pig atrial muscles in vitro without influence upon the post-rest potentiation phenomenon. Met also strengthened the inhibition of m-Nif on the CaCl2-induced contraction of rabbit pulmonary arteries. m-Nif plus Met further suppressed the responce of the spontaneous beating right atria to norepinephrine in vitro as compared with the either alone. In anaesthetized dogs, systemic bloodpressure, total peripheral resistance and heart rate were decreased and cardiac index was increased by m-Nif (0.25 mg·kg-1, intraduodenally). The effect of increasing cardiac index of m-Nif was significantly counteracted and the decrease of heart rate was potentiated by the combination with Met (1.25 mg·kg-1). The results above indicate the Met can enhance the anti-calcium effects of m-Nif on cardiac and vascular smooth muscle, probably due to Met strengthening the inhibition of m-Nif on influx of extracellular calcium in the tissues.