Khatter J C, Agbanyo M, Navaratnam S, Hoeschen R J
Department of Medicine, University of Manitoba, Winnipeg, Canada.
Dev Pharmacol Ther. 1989;12(3):128-36.
In the present study we examined (1) the arrhythmogenic toxicity of ouabain (5 micrograms/kg/min intravenously) in anesthetized guinea pigs of 1-5 days and 3 months of age, and (2) the state of Na+-Ca2+ in the sarcolemmal vesicles isolated from these age groups. Guinea pigs of 1-5 days old tolerated 75% more ouabain than the young adults without significant alteration in the maximal inotropic response. Sodium-dependent 45Ca2+ uptake was substantially lower in the vesicles isolated from hearts of 3-day-old animals, which was characterized by a lower rate of 45Ca2+ uptake (60% Vmax), as compared to the young adults. There was no significant difference in the affinity for 45Ca2+ (Km). The apparent rate of Na+-dependent 45Ca2+ efflux was also lower in the vesicles from 3-day-old guinea pigs. However, the percent extrusion of 45Ca2+ appeared to be unchanged.
在本研究中，我们检测了：（1）哇巴因（5微克/千克/分钟静脉注射）对1至5日龄和3月龄麻醉豚鼠的致心律失常毒性；（2）从这些年龄组分离的肌膜囊泡中Na⁺-Ca²⁺的状态。1至5日龄的豚鼠比年轻成年豚鼠对哇巴因的耐受性高75%，且最大变力反应无显著改变。从3日龄动物心脏分离的囊泡中，钠依赖性⁴⁵Ca²⁺摄取显著降低，其特点是与年轻成年豚鼠相比，⁴⁵Ca²⁺摄取率较低（60%Vmax）。对⁴⁵Ca²⁺的亲和力（Km）无显著差异。3日龄豚鼠囊泡中钠依赖性⁴⁵Ca²⁺外排的表观速率也较低。然而，⁴⁵Ca²⁺的挤出百分比似乎没有变化。
