Kavak Servet, Emre Mustafa, Tetiker Tamer, Kavak Tuyana, Kolcu Zekeriya, Günay Ismail
Department of Biophysics, Faculty of Medical, Cukurova University, 01330 Adana, Turkey.
Naunyn Schmiedebergs Arch Pharmacol. 2008 Feb;376(6):415-21. doi: 10.1007/s00210-007-0234-y. Epub 2007 Dec 21.
The action potential configuration of the left ventricular papillary muscle as well as the rosiglitazone-dependent changes in ventricular papillary muscle action potential amplitude were studied, and the duration was studied and compared in both healthy and diabetic rats. In this study, we used four groups: (1) nondiabetic control animals (C), (2) rosiglitazone-treated nondiabetic control animals (C+RSG), (3) diabetic animals (D), and (4) rosiglitazone-treated diabetic animals (D+RSG). Diabetes was induced by a single intravenous (i.v.) injection of streptozotocin (STZ). Conventional microelectrode techniques were applied to record action potentials after the establishment of diabetes (8 weeks after STZ treatment). Resting membrane potential (RMP) was decreased significantly in both RSG-treated C and D rats (from -70.2 +/- 0.7 to -63.2 +/- 0.7 and from -69.2 +/- 0.4 to -61.2 +/- 0.4). C+RSG and D+RSG groups showed increase in action potential amplitude compared with C and D groups (from 67.1 +/- 0.8 to 68.2 +/- 0.5 and from 67.1 +/- 0.8 to 80.1 +/- 0.8 and from 68.2 +/- 0.5 to 79.3 +/- 0.3) Depolarization time was significantly prolonged in diabetic rats (12.1 +/- 0.4 to 27.5 +/- 0.9). However, this prolongation in D+RSG group was significantly lower according to D group (from 27.5 +/- 0.9 to 19.2 +/- 0.7). There was no difference between C and C+RSG rats (12.1 +/- 0.4 to 11.6 +/- 0.2). Half repolarization time was also prolonged in diabetic rats (17.5 +/- 0.6 to 59.9 +/- 1.0). Moreover, D+RSG rats showed a slight and statistically insignificant difference according D rats (59.9 +/- 1.0 to 55.9 +/- 1.7). C+RSG rats showed a slight significant increase in half repolarization time compared with C group (17.5 +/- 0.6 to 29.4 +/- 0.7). Treatment of rats with RSG markedly decreased insulin resistance and also increased insulin sensitivity of the heart. Our data suggest that the beneficial effects of RSG treatment on the electrical activities of the diabetic rat papillary appear to be due to the diminished K+ currents, partially related to the decrease of hyperglycemia.
研究了左心室乳头肌的动作电位形态以及罗格列酮依赖的心室乳头肌动作电位幅度变化，并在健康大鼠和糖尿病大鼠中对动作电位持续时间进行了研究和比较。在本研究中，我们使用了四组：（1）非糖尿病对照动物（C），（2）罗格列酮治疗的非糖尿病对照动物（C+RSG），（3）糖尿病动物（D），以及（4）罗格列酮治疗的糖尿病动物（D+RSG）。通过单次静脉注射链脲佐菌素（STZ）诱导糖尿病。在糖尿病建立后（STZ治疗8周后），应用传统微电极技术记录动作电位。RSG治疗的C组和D组大鼠的静息膜电位（RMP）均显著降低（从-70.2±0.7降至-63.2±0.7，从-69.2±0.4降至-61.2±0.4）。与C组和D组相比，C+RSG组和D+RSG组的动作电位幅度增加（从67.1±0.8增至68.2±0.5，从67.1±0.8增至80.1±0.8，从68.2±0.5增至79.3±0.3）。糖尿病大鼠的去极化时间显著延长（从12.1±0.4增至27.5±0.9）。然而，根据D组，D+RSG组的这种延长显著降低（从27.5±0.9降至19.2±0.7）。C组和C+RSG组大鼠之间无差异（从12.1±0.4降至11.6±0.2）。糖尿病大鼠的半复极化时间也延长（从17.5±0.6增至59.9±1.0）。此外，根据D组大鼠，D+RSG组大鼠的半复极化时间有轻微且无统计学意义的差异（从59.9±1.0降至55.9±1.7）。与C组相比，C+RSG组大鼠的半复极化时间有轻微显著增加（从17.5±0.6增至29.4±0.7）。用RSG治疗大鼠显著降低了胰岛素抵抗，也增加了心脏的胰岛素敏感性。我们的数据表明，RSG治疗对糖尿病大鼠乳头肌电活动的有益作用似乎是由于K+电流减少，部分与高血糖的降低有关。
