Insulin-mediated vasodilatation, but not glucose uptake or endothelium-mediated vasodilatation, is enhanced in young females compared with males

• In order to evaluate possible differences between men and women with regard to the ability of insulin to induce vasodilatation, promote glucose uptake and enhance endothelium-dependent vasodilatation, 12 young (22-28 years), non-obese women and 15 corresponding males were subjected to 2 h of euglycaemic hyperinsulinaemia (insulin infusion rate of 56 m-units x min(-1) x m(-2)). Forearm blood flow was measured by venous occlusion plethysmography. Endothelium-dependent vasodilatation was evaluated by the local intra-arterial infusion of methacholine into the brachial artery (2-4 microg/min). The cardiac index was measured by thoracic bioimpedance. A 2 h period of hyperinsulinaemia increased the plasma insulin concentration to a similar degree in both sexes (females, 84 +/- 8.8 m-units/l; males, 87 +/- 7.5 m-units/l), but induced a more marked increase in forearm blood flow in females than in males (+104 +/- 67% and +52 +/- 30% respectively; P<0.01; 95% confidence interval for difference 11-94%). Furthermore, a significant decrease in total peripheral resistance (-20 +/- 6.9%; P<0.01) and an increase in cardiac index (+23 +/- 13%; P<0.01) were seen in women only (P<0.05 compared with men). Blood pressure and heart rate were not altered in either sex. Whole-body insulin-mediated glucose uptake and forearm glucose uptake did not differ between the sexes, and the ability of insulin to enhance endothelium-dependent vasodilatation (+19%; P<0.01) was similar in men and women. In conclusion, the present study shows that the ability of insulin to cause vasodilatation was greater in non-obese young women compared with men. However, no differences between the sexes were seen with regard to insulin-mediated glucose uptake and the ability of insulin to enhance endothelium-dependent vasodilatation.

Nyckelord

Adult

Brachial Artery/physiology

Confidence Intervals

Electric Impedance

Endothelium; Vascular/*physiology

Female

Glucose/*metabolism

Humans

Hyperinsulinism/physiopathology

Insulin/blood/*physiology

Male

Methacholine Chloride/diagnostic use

Plethysmography

Sex Characteristics

Vascular Resistance/physiology

Vasodilation/*physiology

MEDICINE

MEDICIN

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