MacConaill M
Department of Pharmacology, University of Ottawa, Canada.
Cardiovasc Res. 1987 Jun;21(6):463-8. doi: 10.1093/cvr/21.6.463.
The median single pulse ventricular fibrillation threshold of 56 determinations in eight isolated rabbit hearts perfused with a Krebs-Henseleit solution was 36 mA, with a range from 12.5 to above 50 mA. The fibrillation threshold remained in the same range when the potassium concentration in the perfusing fluid was decreased from its normal 5.6 mmol.litre-1 to as low as 1.8 mmol.litre-1. A further decrease in potassium concentration reduced the fibrillation threshold to a median value of 1.6 mA in nine determinations on six hearts. With a 1.6 mmol.litre-1 potassium concentration, thresholds were in either the high or the low range depending on the individual heart. A pronounced shortening of refractory period and an earlier vulnerable period were associated with the sharp change in fibrillation threshold; the diastolic extrasystolic threshold, cycle length, and RT interval duration increased in a more linear manner as the potassium concentration was lowered.
在8个用克雷布斯 - 亨塞尔特溶液灌注的离体兔心脏中进行的56次测定，单脉冲心室颤动阈值的中位数为36毫安，范围为12.5至50毫安以上。当灌注液中的钾浓度从正常的5.6毫摩尔·升⁻¹降至低至1.8毫摩尔·升⁻¹时，颤动阈值仍保持在相同范围内。钾浓度进一步降低，在对6个心脏进行的9次测定中，颤动阈值降至中位数1.6毫安。在钾浓度为1.6毫摩尔·升⁻¹时，阈值根据个体心脏处于高范围或低范围。不应期的明显缩短和更早的易损期与颤动阈值的急剧变化相关；随着钾浓度降低，舒张期期外收缩阈值、心动周期长度和RT间期持续时间以更线性的方式增加。
