Baum V C, Klitzner T S
Department of Anesthesiology, UCLA School of Medicine 90024-1778.
Dev Pharmacol Ther. 1993;20(1-2):1-8.
Heart muscle is dependent on the entry of calcium from the extracellular fluid to support contraction, and neonatal hearts are particularly sensitive to reductions in transsarcolemmal entry of calcium. Accordingly, this study evaluated the ability of the calcium channel agonist BAY K8644 to prevent or reverse the myocardial depressant effects of halothane or isoflurane in right ventricular papillary muscles from neonatal rabbits. The ability of BAY K8644 to reverse reductions in force (F) and dF/dt (halothane and isoflurane) or prevent reduction (halothane) was studied. Halothane decreased F to 24 +/- 2% of baseline values (p = 0.001). The addition of BAY K8644 reversed F to only 54 +/- 3% of baseline (p = 0.001 vs. baseline and p = 0.002 vs. halothane alone). Isoflurane decreased F to 20 +/- 2% of baseline (p = 0.001) with a return to 45 +/- 4% of baseline with the addition of BAY K8644 (p = 0.0001 vs. baseline and p = 0.0025 vs. isoflurane alone). With BAY K8644 in the bath prior to the addition of halothane, halothane decreased F to 38 +/- 4% of baseline (p = 0.001). dF/dt mirrored changes in F in all studies. These data show that a calcium channel agonist is only partially effective in modulating volatile anesthetic-induced depression in neonatal rabbit ventricular papillary muscle.
心肌依赖细胞外液中钙的进入来支持收缩，而新生心脏对跨肌膜钙进入的减少尤为敏感。因此，本研究评估了钙通道激动剂BAY K8644预防或逆转氟烷或异氟烷对新生兔右心室乳头肌心肌抑制作用的能力。研究了BAY K8644逆转力（F）和dF/dt降低（氟烷和异氟烷）或预防降低（氟烷）的能力。氟烷使F降至基线值的24±2%（p = 0.001）。添加BAY K8644后，F仅逆转至基线的54±3%（与基线相比p = 0.001，与单独使用氟烷相比p = 0.002）。异氟烷使F降至基线的20±2%（p = 0.001），添加BAY K8644后恢复至基线的45±4%（与基线相比p = 0.0001，与单独使用异氟烷相比p = 0.0025）。在添加氟烷之前先在浴槽中加入BAY K8644，氟烷使F降至基线的38±4%（p = 0.001）。在所有研究中，dF/dt与F的变化情况一致。这些数据表明，钙通道激动剂在调节新生兔心室乳头肌挥发性麻醉药诱导的抑制方面仅部分有效。
