在暴露于蛋白激酶C激动剂的蛙骨骼肌纤维中不存在去横小管(英文)

ABSENCE OF DETUBULATION IN FROG TWITCH MUSCLE FIBRES EXPOSED TO PROTEIN KINASE C ACTIVATOR

过去的工作表明，经12，13-二丁基佛波酯（PDBu，蛋白激酶C激动剂）作用的蛙骨骼肌纤维出现兴奋收缩去耦联。为了了解这种去耦联是否由去横小管引起，本工作研究了细胞内诱发的动作电位。在用渗透压法去横小管后，表明存在完整横小管的动作电位的后去极化逐渐消失。但是，从经1μmol／LPDBu作用12或24h肌纤维中记录到的动作电位依然存在后去极化。上述结果提示，暴露于PDBu的蛙骨骼肌纤维的横小管完整。因而，由PDBu引起的兴奋收缩去耦联的机制仍有待阐明。

It has been shown that excitation-contraction(e-c) uncoupling occurred in frog twitch muscle fibres exposed to phorbol 12, 13-dibutyrate (PDBu), a protein dinase C activator. To investigae if this uncoupling results from detubtilation of the transverse tubules, intracellularly evoked action potentials were examined.The after-depolarization of the action potential, representing intact transverse tubules was gradally abolished by osmotic detubulation, while those obtained from the fibres incubated in 1 μmol/L PDBu for 12 or 24 h still possessed the after-depodrization. Thus, it showed that the transverse tubdes were shll intact in frog twitch muscle fibres after exposure to PDBu. The mechedsm of e-c uncoupling induced by PDBu remains to be clarified.