Ellingsen O, Vengen O A, Ilebekk A
Institute for Experimental Medical Research, Ullevaal Hospital, University of Oslo, Norway.
Am J Physiol. 1987 Oct;253(4 Pt 2):H799-810. doi: 10.1152/ajpheart.1987.253.4.H799.
The changes in myocardial K+ balance during alpha- and beta-adrenoceptor stimulation were compared in 10 anesthetized open-chest pigs by intracoronary isoproterenol and phenylephrine infusions. K+ concentration was continuously recorded by polyvinyl chloride catheter-valinomycin minielectrodes in arterial and coronary sinus blood. The arterial-coronary sinus difference and accumulated myocardial K+ uptake were calculated after computerized data sampling. Isoproterenol (2.5 nmol/min ic) reduced coronary sinus K+ transiently to a nadir of 0.37 (0.23-0.53) mM (median and 95% confidence interval) below control. The accumulated K+ uptake amounted to 139 (63-215) mumol/100 g. After beta-blockade by propranolol, phenylephrine (100 nmol/min ic) induced a transient coronary sinus K+ lowering of 0.16 (0.13-0.21) mM and an accumulated K+ uptake of 30 (20-41) mumol/100 g, both values less than those of isoproterenol (P less than 0.001). Myocardial contractility increased only during isoproterenol infusion, arterial blood pressure rose slightly by phenylephrine, but changes in myocardial O2 extraction and lactate uptake did not indicate cardiac ischemia. We conclude that both alpha- and beta-adrenoceptor stimulation induce a myocardial K+ uptake presumably due to increased Na-K pump activity, the latter more efficiently.
通过冠状动脉内输注异丙肾上腺素和去氧肾上腺素，比较了10只麻醉开胸猪在α和β肾上腺素能受体刺激期间心肌钾平衡的变化。用聚氯乙烯导管-缬氨霉素微型电极连续记录动脉血和冠状窦血中的钾浓度。经计算机数据采样后计算动脉-冠状窦差值和累积心肌钾摄取量。异丙肾上腺素（2.5 nmol/min冠脉内）使冠状窦钾浓度短暂降至比对照低0.37（0.23 - 0.53）mM的最低点（中位数和95%置信区间）。累积钾摄取量为139（63 - 215）μmol/100 g。在用普萘洛尔进行β受体阻断后，去氧肾上腺素（100 nmol/min冠脉内）使冠状窦钾浓度短暂降低0.16（0.13 - 0.21）mM，累积钾摄取量为30（20 - 41）μmol/100 g，这两个值均低于异丙肾上腺素（P < 0.001）。仅在输注异丙肾上腺素期间心肌收缩力增加，去氧肾上腺素使动脉血压略有升高，但心肌氧摄取和乳酸摄取的变化未提示心肌缺血。我们得出结论，α和β肾上腺素能受体刺激均诱导心肌摄取钾，推测是由于钠钾泵活性增加，后者更有效。
