Higher small arterial elasticity in hypertensive patients treated with angiotensin II receptor blockers

Non-invasive measures of tissue autofluorescence are increased in Type 1 diabetes complications and correlate with a non-invasive measure of vascular dysfunction

OBJECTIVE

To determine if ocular and skin autofluorescence, reflecting advanced glycation end-products, and vascular stiffness correlate in non-diabetic and Type 1 diabetic subjects and if levels differ by diabetes status.

RESEARCH DESIGN AND METHODS

Patients with Type 1 diabetes (n = 69, 19 with and 50 without vascular complications) and 60 subjects without diabetes (control) had ocular and skin autofluorescence and pulse-wave analysis performed in the fasted state. Correlations between measures within groups used the Pearson or Spearman correlation-coefficient and measures between groups were compared by ANOVA.

RESULTS

Lens and skin autofluorescence correlated in control (r = 0.58, P = 0.0001) and in Type 1 diabetes (r = 0.53, P = 0.001). Corneal autofluorescence correlated with lens (r = 0.53, r = 0.52, P = 0.0001) and skin autofluorescence (r = 0.34, P = 0.01 and r = 0.49, P = 0.00001) in control and Type 1 diabetes respectively. In Type 1 diabetes, small and large artery elasticity correlated inversely and systemic vascular resistance correlated positively with skin autofluorescence (all P = 0.001), and with lens and corneal autofluorescence (all P < 0.03). In Type 1 diabetes tissue advanced glycation end-products correlated with C-reactive protein and inversely with the estimated glucose disposal rate and with circulating advanced glycation end-product levels. Relative to non-diabetic subjects, lens, corneal and skin fluorescence were increased (all P < 0.001) and small artery elasticity was decreased in diabetes (P = 0.04). Lens, corneal and skin autofluorescence were greater (all P = 0.0001) in patients with Type 1 diabetes with complications compared to those without complications, but small artery elasticity did not differ significantly.

CONCLUSIONS

Ocular and skin autofluorescence and vascular stiffness correlate in non-diabetic and Type 1 diabetes subjects and are increased in Type 1 diabetes. Tissue advanced glycation end-products correlate with vascular risk factors, including circulating advanced glycation end-products.

Association of pulse pressure, arterial elasticity, and endothelial function with kidney function decline among adults with estimated GFR >60 mL/min/1.73 m(2): the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

The association of subclinical vascular disease and early declines in kidney function has not been well studied.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Multi-Ethnic Study of Atherosclerosis (MESA) participants with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) with follow-up of 5 years.

PREDICTORS

Pulse pressure, small (SAE) and large arterial elasticity (LAE), and flow-mediated dilation.

OUTCOMES

Kidney function decline.

MEASUREMENTS

SAE and LAE were measured by pulse contour analysis of the radial artery. Kidney function was assessed by eGFR based on serum creatinine (eGFR(SCr)) and cystatin C (eGFR(SCysC)).

RESULTS

For 4,853 adults, higher pulse pressure and lower SAE and LAE had independent and linear associations with faster rates of kidney function decline. Compared with persons with pulse pressure of 40-50 mm Hg, eGFR(SCysC) declines were 0.29 (P = 0.006), 0.56 (P < 0.001), and 0.91 (P < 0.001) mL/min/1.73 m(2)/y faster in persons with pulse pressure of 50-60, 60-70, and >70 mm Hg, respectively. Compared with the highest quartile of SAE (most elastic), eGFR(SCysC) declines were 0.26 (P = 0.009), 0.35 (P = 0.001), and 0.70 (P < 0.001) mL/min/1.73 m(2)/y faster for the second, third, and fourth quartiles, respectively. For LAE, compared with the highest quartile, eGFR(SCysC) declines were 0.28 (P = 0.004), 0.58 (P < 0.001), and 0.83 (P < 0.001) mL/min/1.73 m(2)/y faster for each decreasing quartile of LAE. Findings were similar for eGFR(SCr). In contrast, for 2,997 adults with flow-mediated dilation and kidney function measures, flow-mediated dilation was not associated significantly with kidney function decline. For every 1-standard deviation greater flow-mediated dilation, eGFR(SCysC) and eGFR(SCr) changed by 0.05 (P = 0.3) and 0.06 mL/min/1.73 m(2)/y (P = 0.04), respectively.

LIMITATIONS

We had no direct measure of GFR, in common with nearly all large population-based studies.

CONCLUSIONS

Higher pulse pressure and lower arterial elasticity, but not flow-mediated dilation, were associated linearly and independently with faster kidney function decline in persons with eGFR ≥60 mL/min/1.73 m(2). Future studies should investigate whether treatments to decrease the stiffness of large and small arteries may slow the rate of kidney function loss.

Noninvasive assessment of left atrial function by strain rate imaging in patients with hypertension: a possible beneficial effect of renin-angiotensin system inhibition on left atrial function

Renin-angiotensin system (RAS) inhibitors are likely to reduce the development of atrial fibrillation by preventing atrial fibrosis. Strain rate (SR) imaging is a novel echocardiographic technique to quantify left atrial (LA) function. However, it has not been determined whether SR imaging is applicable for detection of LA dysfunction in hypertensive (HT) patients. We used SR imaging to assess alteration in LA function in HT patients and its modification by RAS inhibitors. SR imaging was performed in 80 HT patients and 50 age-matched normotensive (NT) subjects. HT patients were divided into two groups according to left ventricular hypertrophy (LVH) and LA dilatation. Peak SR was measured at each LA segment (septal, lateral, posterior, anterior, and inferior) and mean peak systolic SR (SR-LAs) was calculated by averaging data in each segment. Mean SR-LAs levels in the dilated LA group (1.97+/-0.45 s(-1), n=25) and non-dilated LA group (2.15+/-0.57 s(-1), n=55) were significantly (p<0.05) lower than that in NT subjects (2.53+/-0.71 s(-1)). Irrespective of the presence or absence of LVH, mean SR-LAs in HT patients was lower than that in NT subjects. When RAS inhibitors were used, the mean SR-LAs level in the non-dilated LA group was equivalent to that in NT subjects. In HT patients, mean SR-LAs, an index of LA reservoir function, decreases before development of LA enlargement and LVH. Treatment with RAS inhibitors appears to preserve LA reservoir function in HT patients without dilated LA. SR imaging can detect LA dysfunction in HT patients and is useful for evaluation of the therapeutic benefit on LA reservoir function.

Valsartan improves the lower limit of cerebral autoregulation in rats

The effects of angiotensin II type 1 receptor blockers (ARBs) on cerebral blood flow (CBF) autoregulation have not been fully clarified. Thus, we examined the acute effect of valsartan, the most selective ARB, on CBF autoregulation in spontaneously hypertensive rats. Intravenous administration of valsartan (0.3 mg/kg) reduced the mean arterial pressure (MAP) from 184+/-5 (mean+/-SEM) to 174+/-5 mmHg (p<0.001) without affecting CBF as measured by laser-Doppler flowmetry. The lower limit of CBF autoregulation (the MAP at which the CBF was 80% of the baseline value) in the valsartan-treated group (122+/-3 mmHg) was significantly lower than that in the control group (135+/-4 mmHg, p<0.05). Reverse transcribed-polymerase chain reaction and immunohistochemical staining demonstrated that both angiotensin II type 2 receptors and angiotensin II type 1 receptors (AT1Rs) were expressed in endothelial and smooth muscle cells of the rat cerebral arteries. These results suggest that specific inhibition of AT1Rs in the cerebral circulation causes the leftward shift of the lower limit of autoregulation.