Effects of Calcium Channel Blockers on Strophanthidin Actions in Canine Purkinje Fibers

鈣離子阻斷劑對洋地黃藥物心臟作用的影響

呂偉明(Wei-Ming Lue) ； 林正一(Cheng-I Lin) ； 盧信祥(Hsin-Hsiang Lu)

《The Chinese Journal of Physiology》 28卷x期 (1985/06) Pp. 1-12

摘要

木實驗研究比較鈣離子阻斷劑diltiazem及verapamil對洋地黃藥物strophanthidin心臟作用的影響。在3×10^(-7)M劑量時，兩者對離體狗心室Purkinje纖維動作電位影響很小，但顯著抑制收縮張力。Diltiazem延長strophanthidin (3×10^(-6)M)產生最大增強收縮力作用所需時間，並延遲自動快速節律的出現。在多數(6/8)標本verapamil有類似於diltiazem的作用，但少數(2/8)標本當有verapamil存在時strophan thidin不再有增強收縮作用，此種現象可以升高鈣離子來對抗。
木研究結果顯示在狗心室傳導組織，diltiazem及verapamil可以經由減少細飽鈣離子來抑制洋地黃藥物之強心及心律不整作用，兩者中以verapamil的抑制作用較大。

並列摘要

Lue, Wei-Ming, Cheng-I Lin and Hsin-Hsiang Lu: Effects of calcium channel blockers on strophanthidin actions in canine purkinje fibers. Chinese J. Physiol. 28:1-12, 1985. The effects of 3×10^(-7) M diltiazem and verapamil on the electrical and mechanical activity of canine Purkinje fibers were studied in the absence and presence of strophanthidin. Diltiazem or verapamil alone had little effect on the transmembrane potential characteristics but decreased moderately the force of contraction (-32±8% and -46±6%, respectively). The suppressive effect could be reversed by washing with drug-free Tyrode solution. In the presence of diltiazem, 3×10^(-6) M strophanthidin increased the force of contraction as usual but the time to peak force and the time to onset of spontaneous action potentials were significantly prolonged (+32±6% and +122±35%, respectively). In the presence of. verapamil, strophanthidin produced similar effects in 6 of 8 preparations. But in the other 2 preparations, strophanthidin induced little or no positive inotropic effect and the fibers quickly became inexcitable. The excitability could be restored by increasing [Ca(superscript ++)]. The above findings suggest that, in canine Purkinje fibers, both calcium channel blockers delayed the inotropic and arrhythmogenic effects, of strophanthidin by decreasing the cellular calcium. Verapamil had a greater suppressive effect than diltiazem.

並列關鍵字

diltiazem ； verapamil ； strophanthidin ； purkinje fibers ； action potentials ； contractile force ； spontaneous discharges