Skin blood flow and nitric oxide during body heating in type 2 diabetes mellitus.

Individuals with type 2 diabetes mellitus (T2DM) often exhibit microvascular dysfunction that may contribute to impaired thermoregulation, but potential mechanisms remain unclear. Our goals were to quantify skin blood flow responses and nitric oxide-mediated vasodilation during body heating in individuals with T2DM compared with nondiabetic control subjects of similar age. We measured skin blood flow (laser-Doppler flowmetry) in conjunction with intradermal microdialysis of N(G)-nitro-l-arginine methyl ester (l-NAME; nitric oxide synthase inhibitor) or vehicle during 45-60 min of whole body heating (WBH) in 10 individuals with T2DM and 14 control subjects.

Effects of testosterone and estradiol on cutaneous vasodilation during local warming in older men.

Microvascular vasodilation in humans can become impaired with age, leading to cardiovascular diseases ranging from mild to life-threatening. Reproductive hormones may confer some protection on the vascular system in women; however, it is unclear whether the same is true in men. Our goal was to evaluate the impact of four hormonal conditions (testosterone only, estradiol only, testosterone and estradiol, no testosterone and no estradiol) on microvascular vasodilator responsiveness in the skin of older men.

Contribution of nitric oxide to cutaneous microvascular dilation in individuals with type 2 diabetes mellitus.

Microvascular pathophysiology associated with type 2 diabetes mellitus (T2DM) contributes to several aspects of the morbidity associated with the disease. We quantified the contribution of nitric oxide (NO) to the cutaneous vasodilator response to nonpainful local warming in subjects with T2DM (average duration of diabetes mellitus 7 +/- 1 yr) and in age-matched control subjects. We measured skin blood flow in conjunction with intradermal microdialysis of N(G)-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) or vehicle during 35 min of local warming to 42 degrees C.

Beta-2 adrenergic receptor polymorphisms and the forearm blood flow response to mental stress.

Circulating epinephrine plays an important role in skeletal muscle vasodilation during mental stress. Normotensive adults homozygous for glycine (Gly) of the Arg16/Gly beta2-adrenergic receptor polymorphism have a greater forearm beta2-receptor mediated vasodilation and a higher cardiac output response to isometric handgrip than arginine (Arg) homozygotes. To test the hypothesis that the Arg16/Gly beta2-adrenergic receptor polymorphism affects the forearm blood flow (FBF) and hemodynamic response to mental stress, and whether venous catecholamine concentrations predicted these responses, we measured venous epinephrine, norepinephrine, heart rate (HR), arterial pressure (Finapres), and FBF during mental stress in healthy subjects homozygous for Gly16 (n = 30; mean age +/- SE: 30 +/- 1.

Arg16/Gly beta2-adrenergic receptor polymorphism alters the cardiac output response to isometric exercise.

Normotensive adults homozygous for glycine (Gly) of the Arg16/Gly beta2-adrenergic-receptor polymorphism have 1) greater forearm beta2-receptor mediated vasodilation and 2) a higher heart rate (HR) response to isometric handgrip than arginine (Arg) homozygotes. To test the hypothesis that the higher HR response in Gly16 subjects serves to maintain the pressor response [increased cardiac output (CO)] in the setting of augmented peripheral vasodilation to endogenous catecholamines, we measured continuous HR (ECG), arterial pressure (Finapres), and CO (transthoracic echocardiography) during isometric, 40% submaximal handgrip to fatigue in healthy subjects homozygous for Gly (n = 30; mean age +/- SE: 30 +/- 1.2, 13 women) and Arg (n = 17, age 30 +/- 1.