Insulin resistance and myocardial hypertrophy in the attenuated reduction in mean arterial pressure after a glucose load in hypertensive patients

RESUMO

Although long recognized, the vasodilator effect of insulin has been relatively neglected over the last few years. Recent reports have focused on the sympathetic and antinatriuretic actions of this hormone. In the first part of the present study we characterized the reduction in blood pressure after a glucose load in hypertensive patients with and without insulin resistance. fourteen hypertensive Caucasian patients and ten Caucasian controls were submitted to a standard oral glucose tolerance test (OGTT) and intravenous insulin tolerance test (15-min ITT). In the hypertensive patients with insulin resistance the reduction in mean arterial presure (MAP) after a glucose load was blunted (6.7 ñ 1.7 per cent (N = 5)) when compared to insulin-sensitive (12.9 ñ 1.1 per cent (N = 9)) and normal subjects (10.1 ñ 0.8 per cent). IN the second part of the study we investigated whether hypertensive patients with myocardial hypertrophy were more insulin resistant than hypertensive individuals with a normal cardiac mass. The glucose disappearance rate (Kitt) was lower in hypertensive patients with myocardial myocardial hypertensive patients with myocardial hypertrophy (6.0 ñ 1.0 (N = 6)) when compared to hypertensive patients without myocardial hypertrophy (8.2 ñ 1.0 per cent/min (N = 8)), suggesting an association between this organomegaly and insulin resistance. In conclusion, our results suggested that 1) insulin resistance, rather than hyperinsulinemia, acts as a risk factor for the development of hypertension, because of insulin's inability to decrease MAP in this situation, and 2) there is an association between left ventricular hypertrophy and insulin resistance in hypertensive patients