Komai H, Rusy B F
Department of Anesthesiology, University of Wisconsin, Madison.
Anesthesiology. 1994 Oct;81(4):946-52. doi: 10.1097/00000542-199410000-00021.
While thiopental is known to inhibit the myocardial transsarcolemmal influx of Ca2+, the effect of thiopental on sarcoplasmic reticular Ca2+ release has not been characterized.
Isolated papillary muscles of rabbits were used. We measured postrest contractions to assess the Ca2+ release by sarcoplasmic reticulum in response to electrical stimulation. Contractures induced by rapid cooling were used as an index of Ca2+ content of sarcoplasmic reticulum. The effect of thiopental on the availability of extracellularly derived Ca2+ was evaluated from measurements of contractions at 0.1 Hz in the presence of 1 microM ryanodine.
Thiopental sodium (10, 20, and 30 mg/l; 38, 76, and 113 microM) inhibited the postrest contraction but not the contracture induced by rapid cooling. In the presence ryanodine, thiopental inhibited the postrest contraction elicited after 10 s of rest after 2-Hz stimulation much less than the steady-state contraction at 0.1 Hz (beat interval 10 s). Thiopental inhibited the postrest contraction (no ryanodine present) more strongly than did Ni2+ (an inhibitor of the transsarcolemmal Ca2+ influx) when the contraction at 0.1 Hz in the presence of ryanodine was inhibited to the same extent.
These results suggest that thiopental decreases sarcoplasmic reticulum Ca2+ release induced by electrical stimulation and inhibits the ryanodine-induced efflux of sarcoplasmic reticulum Ca2+.
虽然已知硫喷妥钠可抑制钙离子经心肌肌膜的内流，但硫喷妥钠对肌浆网钙离子释放的影响尚未明确。
使用兔离体乳头肌。我们测量静息后收缩以评估肌浆网对电刺激的钙离子释放反应。快速冷却诱导的挛缩用作肌浆网钙离子含量的指标。通过在1微摩尔兰尼碱存在下测量0.1赫兹收缩来评估硫喷妥钠对细胞外源性钙离子可用性的影响。
硫喷妥钠（10、20和30毫克/升；38、76和113微摩尔）抑制静息后收缩，但不抑制快速冷却诱导的挛缩。在存在兰尼碱的情况下，硫喷妥钠对2赫兹刺激后10秒静息引发的静息后收缩的抑制作用远小于0.1赫兹（搏动间隔10秒）时的稳态收缩。当在兰尼碱存在下0.1赫兹收缩被抑制到相同程度时，硫喷妥钠比镍离子（肌膜钙离子内流抑制剂）更强烈地抑制静息后收缩。
这些结果表明硫喷妥钠可减少电刺激诱导的肌浆网钙离子释放，并抑制兰尼碱诱导的肌浆网钙离子外流。
