Alterations in perivascular adipose tissue structure and function in hypertension.

We studied the structural and the functional alterations of perivascular adipose tissue (PVAT) in hypertension with spontaneously hypertensive rats (SHR). Measured with dual energy X-ray absorptiometry, a smaller body fat mass and a greater lean mass were found in SHR than in Wistar-Kyoto (WKY) rats, while body weight was comparable between them. In the thoracic PVAT, the density and the total number of brown adipocytes were greater in SHR than in WKY rats, while the cross section area of PVAT was similar between them.

Mechanisms for perivascular adipose tissue-mediated potentiation of vascular contraction to perivascular neuronal stimulation: the role of adipocyte-derived angiotensin II.

In rat mesenteric arteries we have recently found that perivascular adipose tissue (PVAT) promoted vasoconstriction to perivascular neuronal activation (by electrical field stimulation, EFS) through generation of superoxide. In this study, we examined the role of adipocyte-generated angiotensin II in PVAT-mediated potentiation of contraction to nerve stimulation. In rat mesenteric PVAT, the presence of angiotesinogen and angiotensin I-converting enzyme (ACE) mRNA was confirmed by RT-PCR.

Alteration of perivascular adipose tissue function in angiotensin II-induced hypertension.

We studied the role of perivascular adipose tissue (PVAT) in the control of vascular function in an in vivo experimental model of hypertension produced by angiotensin II infusion by osmotic minipump in adult male Wistar rats. Two weeks after infusion with angiotensin II, blood pressure in treated rats was significantly elevated but heart rate was reduced compared with control rats infused with physiological saline. Contraction of aorta from the 2 groups of rats in response to phenylephrine or serotonin was significantly attenuated by the presence of PVAT in both the presence and absence of endothelium.

Endothelium-dependent relaxation factor released by perivascular adipose tissue.

Objective: Recent studies have demonstrated that perivascular adipose tissue (PVAT) releases vascular relaxation factor(s), but the identity of this relaxation factor remains unknown. Here, we examined if angiotensin 1-7 [Ang-(1-7)] is one of the relaxation factors released by PVAT.

Method: Morphological and functional methods were used to study aorta from adult Wistar rats.

Effects of hyperglycemia on the modulation of vascular function by perivascular adipose tissue.

Objective: To study the acute and chronic effect of hyperglycemia on perivascular adipose tissue (PVAT) function in rat aorta.

Method: Alterations in PVAT function in rat aorta incubated with 22 mmol/l D-glucose for 30 min and in aorta from streptozotocin (STZ)-induced diabetic rats were studied.

Results: Incubation with D-glucose caused an attenuation of contraction in response to phenylephrine, both in the presence and absence of endothelium, whereas removal of PVAT eliminated this attenuation effect.

Effects of fetal and neonatal exposure to nicotine on blood pressure and perivascular adipose tissue function in adult life.

In Wistar rats, maternal exposure to nicotine was shown to impair the inhibitory function of perivascular adipose tissue on vascular contractility in the aorta of the offspring. It is not known whether an impairment of perivascular adipose tissue function occurs in smaller arteries, and whether the control of blood pressure is affected. Here we studied the blood pressure effects and the alteration of perivascular adipose tissue function in mesenteric arteries of the offspring born to Wistar-Kyoto rat (WKY) dams exposed to nicotine.

Superoxide anion mediates angiotensin II-induced potentiation of contractile response to sympathetic stimulation.

Angiotensin II is known to potentiate vasoconstriction induced by electrical field stimulation (EFS), but the underlying mechanisms for this potentiation are not fully understood. This study was designed to investigate the role of superoxide anion in the potentiation effects of angiotensin II. Contraction of rat mesenteric arterial segments was induced by perivascular nerve stimulation with EFS, and superoxide production was measured with lucigenin-enhanced chemiluminescence.

Thyroid dysfunction in patients with Down syndrome.

Background: The close relationship between thyroid disorder and Down syndrome (DS) had been widely reported in the literature. The aim of this study was to assess the prevalence rate and the pattern of thyroid dysfunction in DS in Taiwan.

Methods: A total of 50 Down syndrome (DS) patients from Yang-Ming Home for Disabled, were recruited.

Elevated blood pressure in transgenic lipoatrophic mice and altered vascular function.

The role of perivascular fat in the control of vascular function was studied using lipoatrophic A-ZIP/F1 transgenic mice. Only a small amount of brown fat was found around the aorta but not around mesenteric arteries. Blood pressure of A-ZIP/F1 mice became higher than wild-type (WT) mice from 10 weeks of age.

Perivascular adipose tissue promotes vasoconstriction: the role of superoxide anion.

Objectives: Recent studies have demonstrated that perivascular adipose tissue (PVAT) releases vascular relaxation factor(s). In this study, we examined if PVAT releases other vasoactive factors in response to perivascular nerve activation by electrical field stimulation (EFS).

Methods And Results: In Wistar-Kyoto rats, rings of superior mesenteric artery (MA) with intact PVAT (PVAT (+)) showed a greater contractile response to EFS than rings with PVAT removed (PVAT (-)).