Schmidt T A, Bundgaard H, Olesen H L, Secher N H, Kjeldsen K
Copenhagen University Heart Centre, Rigshospitalet, Denmark.
Cardiovasc Res. 1995 Apr;29(4):506-11.
The aim was to evaluate whether digitalisation of heart failure patients affects extrarenal potassium handling during and following exercise, and to assess digoxin receptor occupancy in human skeletal muscle in vivo.
In a paired study of before versus after digitalisation, 10 patients with congestive heart failure underwent identical exercise sessions consisting of three bouts of increasing work rates, 41-93 W, on a cycle ergometer. The final bouts were followed by exercise to exhaustion. The femoral vessels and brachial artery were catheterised. Arterial blood pressure, heart rate, leg blood flow, cardiac output, plasma potassium, haemoglobin, pH, and skeletal muscle receptor occupancy with digoxin in biopsies were determined.
Occupancy of skeletal muscle Na/K-ATPase with digoxin was 9% (P < 0.05). Following digitalisation femoral venous plasma potassium increased by 0.2-0.3 mmol.litre-1 (P < 0.05) at work rates of 69 W, 93 W, and at exhaustion, as well as during the first 3 min of recovery. Following digitalisation the femoral venoarterial difference in plasma potassium increased by 50-100% (P < 0.05) during exercise, and decreased by 66-75% (P < 0.05) during early recovery. Total loss of potassium from the leg increased by 138%. The effects of digitalisation on plasma potassium were not the outcome of changes in haemodynamics, because cardiac output and leg blood flow increased by up to 13% and 19% (P < 0.05), nor was it the outcome of changes in haemoconcentration or pH.
Extrarenal potassium handling is altered as a result of digoxin treatment. This is likely to reflect a reduced capacity of skeletal muscle Na/K-ATPase for active potassium uptake because of inhibition by digoxin, adding to the reduction of skeletal muscle Na/K-ATPase concentration induced by heart failure per se. In heart failure patients, improved haemodynamics induced by digoxin may, however, increase the capacity for physical conditioning. Thus the impairment of extrarenal potassium homeostasis by heart failure and digoxin treatment may be counterbalanced by training.
旨在评估心力衰竭患者的数字化处理是否会影响运动期间及运动后肾外钾的处理，并评估地高辛在人体骨骼肌中的受体占有率。
在一项数字化处理前后的配对研究中，10例充血性心力衰竭患者在自行车测力计上进行相同的运动试验，包括三轮工作强度递增的运动，工作强度为41 - 93瓦。最后一轮运动后持续运动至力竭。对股血管和肱动脉进行插管。测定动脉血压、心率、腿部血流量、心输出量、血浆钾、血红蛋白、pH值以及活检中骨骼肌地高辛受体占有率。
地高辛对骨骼肌钠钾ATP酶的占有率为9%（P < 0.05）。数字化处理后，在69瓦、93瓦的工作强度、力竭时以及恢复的前3分钟，股静脉血浆钾升高了0.2 - 0.3毫摩尔/升（P < 0.05）。数字化处理后，运动期间股静脉与动脉血浆钾的差值增加了50 - 100%（P < 0.05），而在早期恢复期间降低了66 - 75%（P < 0.05）。腿部钾的总丢失量增加了138%。数字化处理对血浆钾的影响并非血流动力学变化的结果，因为心输出量和腿部血流量分别增加了高达13%和19%（P < 0.05），也不是血液浓缩或pH值变化的结果。
地高辛治疗导致肾外钾处理发生改变。这可能反映了由于地高辛的抑制作用，骨骼肌钠钾ATP酶主动摄取钾的能力降低，这进一步加重了心力衰竭本身所导致的骨骼肌钠钾ATP酶浓度降低。然而，在心力衰竭患者中，地高辛诱导的血流动力学改善可能会增加身体适应能力。因此，心力衰竭和地高辛治疗对肾外钾稳态的损害可能会被训练所抵消。
