肼屈嗪对大鼠离体心房变力性和变时性作用的机制。

The mechanisms of the inotropic and chronotropic actions of hydralazine on rat isolated atria.

作者信息

Songkittiguna P, Rand M J

出版信息

Arch Int Pharmacodyn Ther. 1982 Feb;255(2):269-80.

Abstract

The effects of hydralazine on rat isolated atria depend on its concentration. A negative chronotropic effect due to inhibition of spontaneous release of noradrenaline was produced by concentrations of 1 x 10(-5) - 1 x 10(-4) M, but with concentrations of 2 x 10(-4) M or more the negative chronotropic effect was due to a more direct depression of pacemaker activity. A positive chronotropic effect due to release of noradrenaline was produced by a concentration of 2 x 10(-3) M; when this was abolished by reserpine pretreatment or beta-adrenoceptor blockade, the negative chronotropic effect was unmasked or accentuated. A positive inotropic effect was produced by concentrations of 6 x 10(-4) - 2 x 10(-3) M; this effect was not reduced by reserpine or beta-adrenoceptor blockade, but it was absent in a calcium-free medium and was blocked by verapamil.

摘要

肼屈嗪对大鼠离体心房的作用取决于其浓度。浓度为1×10⁻⁵ - 1×10⁻⁴M时，因抑制去甲肾上腺素的自发释放而产生负性变时作用，但浓度为2×10⁻⁴M或更高时，负性变时作用是由于对起搏点活动更直接的抑制。浓度为2×10⁻³M时，因去甲肾上腺素释放而产生正性变时作用；当用利血平预处理或β-肾上腺素受体阻断消除此作用时，负性变时作用被揭示或增强。浓度为6×10⁻⁴ - 2×10⁻³M时产生正性变力作用；此作用不因利血平或β-肾上腺素受体阻断而减弱，但在无钙培养基中不存在，且被维拉帕米阻断。