温度K^＋浓度对培养乳鼠心肌细胞搏动频率的影响

The Effect of Temperature and PotassiumConcentration on Beating Frequancy of Cul- tured Nenatal Rat Heart Ventricular Myocytes

本文观察了３６℃及１４℃时不同Ｋ＋浓度对培养乳鼠心肌细胞搏动频率的影响，发现：①［Ｋ＋］≥１６ｍｍｏｌ／Ｌ时，无论低温还是常温均能迅速诱导心肌细胞停搏；１４℃低温不能降低心肌细胞停搏所需的［Ｋ＋］，但可显著延长心肌细胞的停搏时间。②在一定范围的高Ｋ＋环境中，心肌细胞停搏后，经一段时间能缓慢而不规则复律，以２４ｍｍｏｌ／Ｌ及２８ｍｍｏｌ／Ｌ［Ｋ＋］复律最早，频率最快；加入Ｃａ＋＋－通道拮抗剂，复律的细胞又迅速停搏。说明高［Ｋ＋］致膜电位去极化，Ｎａ＋通道失活的同时，能缓慢激活Ｃａ＋＋通道，引起类似“慢反应细胞”的自动除极。结果提示：在心停搏液中，无论是常温还是低温，１６ｍｍｏｌ／ＬＫ＋足以诱导心肌细胞停搏，且维持时间较长；低温能延长停搏时间。在“温血心”外科，１６ｍｍｏｌ／ＬＫ＋加小剂量Ｃａ＋＋通道拮抗剂，对维持心肌细胞停搏可能有一定益处。

Abstract This Paper Presented a report of efect ofdifferent tempreature(36.0and 14.0)andpotassium concentrations on beating frequancyof cultured nenatal rat cardiac myocytes.Re-sults showed that(1)the myocytes immediate-ly arrested when potassium was more than 16mmol/l,whether hypothermia or normother-mia.Hypothermia alone could not have themyocardial cells arrested,but could postponetheir cardioplegic duration. (2)in a range ofhyperpotassium,the cells was able to retrunebeating gradually after its arresting.The re-turn of beating was the earliest and the beat-ing frequancy was the most quick when theconcentraction of potassium was 24-28mmol/L.If the channel antagonalist was added,thesecells would arrested rapidly. It suggested thathyperpotassium could activate Ca++channelslowly while inducing myocytes membrancepotential depolarization and inactivating Na+channel,similar to the autodepolarizdation ofslow reaction cells.From the above,it conclud- ed that 116mmol/L potassium,whether nor- motherma or hypotherma,was able to inducecell arresteding and keep it in a much longertime.Hypotheria was able to postpone cardio- plegic duration.It would be much better formaintaining the arrest of myocardial cells if16mmol/l potassium combined with a smallamount of Ca++antagonist.