Hof T O, Mackaay A J, Bleeker W K, Houtkooper J M, Abels R, Bouman L N
J Pharmacol Exp Ther. 1980 Feb;212(2):183-9.
Ca (1.1--5.5 mM) acts positive chronotropic on isolated right atria of the rabbit at 38 degrees C. At 34 degrees C, the chronotropic effect was also positive but smaller than at 38 degrees C. At 30 degrees C, the chronotropic effect is variable. Negative and positive chronotrpic effects were observed. At all three temperatures, the magnitude of the effect depended on the cycle length. Mg (0.6--6.0 mM) has a negative chronotropic effect. This effect was not dependent on the cycle length. The relationship between prolongation of the cycle length and the Mg concentration turned out to be linear. The chronotropic effects of Ca and Mg were simply algebraically additive. On the average, Na (77.4--154.8 mM) has no significant chronotropic effect. However, it acts positive chronotropic on fast preparations, although it acts negative chronotropic on slow preparations. So the chronotropic effect of Na depends on the cycle length also.
在38℃时，钙（1.1 - 5.5毫摩尔）对兔离体右心房有正性变时作用。在34℃时，变时作用也是正性的，但比38℃时小。在30℃时，变时作用是可变的，观察到了负性和正性变时作用。在所有这三个温度下，作用的大小取决于心动周期长度。镁（0.6 - 6.0毫摩尔）有负性变时作用。这种作用不依赖于心动周期长度。心动周期长度的延长与镁浓度之间的关系是线性的。钙和镁的变时作用只是简单的代数相加。平均而言，钠（77.4 - 154.8毫摩尔）没有显著的变时作用。然而，它对快速标本有正性变时作用，尽管它对慢速标本有负性变时作用。所以钠的变时作用也取决于心动周期长度。
