Souza M L, Leme C A, Cavicchio J R, Saad M J, Gontijo J A
Disciplina de Medicina Interna, Faculdade de Ciencias Medicas, Universidade Estadual de Campinas, SP, Brasil.
Acta Physiol Pharmacol Ther Latinoam. 1999;49(2):87-92.
There is a paucity of experimental data on the actual mechanism of insulin-induced changes on the myocardial function. In the present study we investigated the myocardial contractile, response to an oral glucose load using echocardiography. Fifteen healthy volunteers were studied after overnight fast and 150 minutes after the oral load of 75 g glucose. Oral glucose load caused an increase in plasma glucose and insulin levels, which was accompanied by a significant increase in left ventricular shortening (from 35.2 +/- 0.7% at baseline, to 38.5 +/- 0.6% and 39 +/- 0.9% at 30 and 60 minutes post glucose load, respectively [P < 0.05 vs baseline]; ejection fraction rose from 0.73% +/- 0.01 to 0.77% +/- 0.01 (P < 0.05); pressure rate product increased from 7.29 +/- 0.2 to 8.31 +/- 0.3 mmHg x beats per min (P < 0.007) and heart rate enhanced from 68.3 +/- 1.9 to 74 +/- 1.6 (P < 0.034) and 75.3 +/- 1.5 beats per min (P < 0.008) at 60 and 90 minutes after glucose, respectively. Meanwhile, mean arterial pressure decreased significantly (10 +/- 1.5%, P < 0.018) when compared to basal values. These results indicate a significant change in the myocardial contractile response to an oral glucose load, probably related to baroreceptor reflex response as well as an overridden by a potent vasodilator action of insulin. Nevertheless, we could not rule out that the cardiac effects may also be due an insulin-induced sympathetic activation or a direct myocardial effect.
关于胰岛素引起心肌功能变化的实际机制，实验数据较少。在本研究中，我们使用超声心动图研究了口服葡萄糖负荷后心肌的收缩反应。对15名健康志愿者进行了研究，他们在过夜禁食后以及口服75克葡萄糖150分钟后接受检测。口服葡萄糖负荷导致血浆葡萄糖和胰岛素水平升高，同时左心室缩短显著增加（从基线时的35.2±0.7%，分别增加到葡萄糖负荷后30分钟时的38.5±0.6%和60分钟时的39±0.9%[与基线相比，P<0.05]）；射血分数从0.73%±0.01升高到0.77%±0.01（P<0.05）；压力速率乘积从7.29±0.2升高到8.31±0.3 mmHg×每分钟心跳次数（P<0.007），心率分别在葡萄糖负荷后60分钟和90分钟时从68.3±1.9升高到74±1.6（P<0.034）和75.3±1.5次/分钟（P<0.008）。同时，与基础值相比，平均动脉压显著降低（10±1.5%，P<0.018）。这些结果表明，口服葡萄糖负荷后心肌收缩反应有显著变化，这可能与压力感受器反射反应有关，也可能是由于胰岛素强大的血管舒张作用占主导。然而，我们不能排除心脏效应也可能是由于胰岛素诱导的交感神经激活或直接的心肌效应。
