Microvascular Endothelial Dysfunction and Enhanced Thromboxane and Endothelial Contractility in Patients with HIV

Abstract

11 background: The prevalence of cardiovascular disease is increased with human immunodeficiency virus (HIV) infection, but the mechanism is unclear. We hypothesized that HIV increases microvascular reactive oxygen species, thereby impairing endothelial function and enhancing contractility.

12 method: Subcutaneous microarterioles were isolated from gluteal skin biopsies in premenopausal, African American, HIV positive women receiving effective anti-retroviral therapy, but without cardiovascular risk factors except for increased body mass index (n=10) and healthy matched controls (n=10). The arterioles were mounted on myographs, preconstricted and relaxed with acetylcholine for: endothelium-dependent relaxation, endothelium-dependent relaxation factor (nitric oxide synthase-dependent relaxation), endothelium-dependent hyperpolarizing factor (potassium-channel dependent relaxation) and endothelium-independent relaxation (nitroprusside). Contractions were tested to endothelium-dependent contracting factor (acetylcholine contraction with blocked relaxation); phenylephrine, U-46,619 and endothelin-1. Plasma L-arginine and asymmetric dimethylarginine were measured by high performance capillary electrophoresis.

13 results: The micro-arterioles from HIV positive women had significantly (% change in tension; P<0.05) reduced acetylcholine relaxation (-51 ± 6 vs. -78 ± 3%), endothelium-dependent relaxation factor (-28 ± 4 vs. -39 ± 3%), endothelium-dependent hyperpolarizing factor (-17 ± 4 vs. -37 ± 4%) and decreased nitric oxide activity (0.16 ± 0.03 vs. 0.70 ± 0.16 Δ unit) but unchanged nitroprusside relaxation. They had significantly enhanced endothelium-dependent contracting factor (+21 ± 6 vs. +7 ± 2%) and contractions to U-46,619 (+164 ± 10 vs. +117 ± 11%) and endothelin-1(+151 ± 12 vs. +97 ± 9%), but not to phenylephrine. There was enhanced reactive oxygen species with acetylcholine (0.11 ± 0.02 vs. 0.05 ± 0.01 Δ unit; P<0.05) and endothelin-1 (0.31 ± 0.06 vs. 0.10 ± 0.02 Δ unit; P<0.05). Plasma L-arginine: assymetric dimethyl arginine rates was reduced (173 ± 12 vs. 231 ± 6 μmol·μmol^-1, P<0.05).

14 conclusion: Premenopausal HIV positive womenhad microvascular oxidative stress with severe endothelial dysfunction and reduced nitric oxide and arginine: assymetric dimethylarginine ratio but enhanced endothelial, thromboxane and endothelin contractions. These microvascular changes may herald later cardiovascular disease.

Keywords: Asymmetric dimethylarginine (ADMA); Cardiovascuar disease (CVD); Endothelial dysfunction; Endothelin-1 (ET-1); Endothelium-dependent relaxing factor (EDRF); Nitric oxide (NO); Reactive oxygen species (ROS); Thromboxane-prostanoid receptors (TP-Rs).

Figure 1

Drawings from myograph tracings of tension in a subcutaneous resistance arteriole from normal subjects (control; solid circles) and a subject infected with HIV (open circles). Norepinephrine (NE) was added to the bath before testing with acetylcholine.

Figure 2

Mean ± SEM values for acetylcholine- or sodium nitroprusside-induced relaxations of subcutaneous vessels from control (broken lines and open circles) or HIV infected (continuous lines and solids circles) women preconstricted with norepinephrine (10^-5 mol·l^-1). Panel A endothelium dependent relaxation (EDR). Panel B endothelium independent relaxation to sodium nitroprusside (EIR). Panel C endothelium dependent relaxation factor responses (EDRF) in vessels incubated with L-N^G-nitroarginine methyl ester (10^-5 mol·l^-1); Panel D endothelium dependent hyperpolarizating factor responses (EDHF) in vessels incubated with L-NAME (10^-5 mol·l^-1) plus apamin (AP, 10^-6 mol·l^-1) and charybotoxin (CTX, 10^-5 mol·l^-1). P values refer to ANOVA with repeated measures. Comparing HIV and control subjects at a single dose: *P<0.05, **P<0.01.

Figure 3

Mean ± SEM values for endothelium dependent contraction factor responses (EDCF) from controls (broken lines and open circles) or HIV infected (continuous lines and solid circles) women in vessels under spontaneous tone incubated with L-NAME plus apamin+charybotoxin. P values refer to ANOVA with repeated measures. Comparison of HIV and controls at a single dose: *P<0.05; **P<0.01.

Figure 4

Mean ± SEM values for vascular contractions to phenylephrine (PE), U-46,619 or endothelin-1(ET-1) from controls (broken lines and open circles) or HIV infected (continuous lines and solid circles) women. P values refer to ANOVA with repeated measures. Comparison of HIV and controls at a single dose: *P<0.05; **P<0.01.

Figure 5

Mean ± SEM values for 10^-5 mol·l^-1 acetylcholine-induced NO activity (Panel A, DAF-FM fluorescence) and 10^-4 mol·l^-1 ACh induced ROS activity in the present of L-NAME plus apamin and CTX (Panel B, Tempo-9-AC fluorescence) and ROS activity with 10^-7 mol·l^-1 endothelin-1 (Panel C) of subcutaneous vessels from controls (open boxes) and HIV infected (closed boxes) women. Compared to control: *P<0.05.