离体兔、豚鼠和大鼠心肌的动作电位时程与力-频率关系
Action potential duration and force-frequency relationship in isolated rabbit, guinea pig and rat cardiac muscle.
作者信息
Szigligeti P, Pankucsi C, Bányász T, Varró A, Nánási P P
机构信息
Department of Physiology, University Medical School of Debrecen, Hungary.
出版信息
J Comp Physiol B. 1996;166(2):150-5. doi: 10.1007/BF00301179.
The effect of action potential duration and elevated cytosolic sodium concentration on the force-frequency relationship in isolated rabbit, guinea pig and rat papillary muscle preparations was studied. Shortening of action potential duration in guinea pig and rabbit from 150-200 ms to values characteristic of rat (20-40 ms), using the K(ATP) channel activator levkromakalim (15 mumol.l-1), markedly reduced the force of contraction and converted the positive force-frequency relationship into negative one at longer pacing cycle lengths. This conversion was greatly enhanced in the presence of acetylstrophanthidin (0.2-1 mumol.l-1), an inhibitor of the Na-K pump. Acetylstrophanthidin (1 mumol.l-1) alone, however, had no effect on the force-frequency relationship. Prolongation of action potential duration in rat with inhibitors of cardiac K channels (4-aminopyridine [10 mmol.l-1] plus tetraethylammonium [2 mmol.l-1) increased the force of contraction and abolished the negative force-frequency relationship observed in rat at longer pacing-cycle lengths. It is concluded that both action potential duration and cytosolic sodium concentration are major determinants of the force-frequency relationship in mammalian myocardium.
研究了动作电位持续时间和胞质钠浓度升高对离体兔、豚鼠和大鼠乳头肌标本中力-频率关系的影响。使用K(ATP)通道激活剂左旋克罗卡林（15 μmol·L-1）将豚鼠和兔的动作电位持续时间从150 - 200毫秒缩短至大鼠特有的值（20 - 40毫秒），在较长的起搏周期长度下，显著降低了收缩力，并将正向力-频率关系转变为负向关系。在钠钾泵抑制剂乙酰洋地黄毒苷（0.2 - 1 μmol·L-1）存在的情况下，这种转变大大增强。然而，单独使用乙酰洋地黄毒苷（1 μmol·L-1）对力-频率关系没有影响。用心脏钾通道抑制剂（4 - 氨基吡啶[10 mmol·L-1]加四乙铵[2 mmol·L-1]）延长大鼠的动作电位持续时间，增加了收缩力，并消除了在较长起搏周期长度下大鼠中观察到的负向力-频率关系。得出的结论是，动作电位持续时间和胞质钠浓度都是哺乳动物心肌中力-频率关系的主要决定因素。
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