Myocardial contractile response to an oral glucose load in normal subjects evaluated by echocardiography

RESUMO

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 accompained by a significant increase in left ventricular shortening (from 35.2 + 0.7 per cent at baseline, to 38.5 + 0.6 per cent and 39 + 0.9 per cent at 30 and 60 minutes post glucose load, respectively [P<0.05 vs baseline]; ejection faction rose from 0.73 per cent + 0.01 to 0.77 per cent + 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 presure decreased significantly (10+1.5 per cent, 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 vasodilatador action of insulin. Nevertheless, we could not rule out the cardiac effects may also be due an insulin-induced sympathetic activation or a direct myocardial effect.