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Université de Fribourg

Understanding the contribution of Guyton's large circulatory model to long-term control of arterial pressure

Montani, Jean-Pierre ; Vliet, Bruce N. Van

In: Experimental Physiology, 2009, vol. 94, no. 4, p. 382-388

With the publication in 1972 of a large computer model of circulatory control, Guyton and colleagues challenged the then prevailing views on how blood pressure and cardiac output were controlled. At that time, it was widely accepted that the heart controlled cardiac output and that peripheral resistance controlled arterial blood pressure. By incorporating the empirically demonstrated concepts of...

Université de Fribourg

Mutation of the circadian clock gene Per2 alters vascular endothelial function

Viswambharan, Hema ; Carvas, João Miguel ; Antic, Vladan ; Marecic, Ana ; Jud, Corinne ; Zaugg, Christian E. ; Ming, Xiu-Fen ; Montani, Jean-Pierre ; Albrecht, Urs ; Yang, Zhihong

In: Circulation, 2007, vol. 115, p. 2188-2195

Background— The circadian clock regulates biological processes including cardiovascular function and metabolism. In the present study, we investigated the role of the circadian clock gene Period2 (Per2) in endothelial function in a mouse model. Methods and Results— Compared with the wild-type littermates, mice with Per2 mutation exhibited impaired...

Université de Fribourg

Increased salt-sensitivity in endothelial nitric oxide synthase–knockout mice

Leonard, Allison M. ; Chafe, Linda L. ; Montani, Jean-Pierre ; Vliet, Bruce N. Van

In: American Journal of Hypertension, 2006, vol. 19, no. 12, p. 1264-1269

Background Although impaired nitric oxide production contributes importantly to salt-sensitivity, the role of the endothelial isoform of nitric oxide synthase (eNOS) has received little attention. In the present study we compared the effects of a high-salt diet on the blood pressure response of eNOS knockout (eNOS−/−) and control (eNOS+/+) mice. Methods Mean arterial pressure (MAP), heart...

Université de Fribourg

Water-induced thermogenesis reconsidered: the effects of osmolality and water temperature on energy expenditure after drinking

Brown, Clive M. ; Dulloo, Abdul G. ; Montani, Jean-Pierre

In: Journal of Clinical Endocrinology and Metabolism, 2006, vol. 91, no. 9, p. 3598-3602

Context: A recent study reported that drinking 500 ml of water causes a 30% increase in metabolic rate. If verified, this previously unrecognized thermogenic property of water would have important implications for weight-loss programs. However, the concept of a thermogenic effect of water is controversial because other studies have found that water drinking does not increase energy...

Université de Fribourg

Mature adipocytes and perivascular adipose tissue stimulate vascular smooth muscle cell proliferation: effects of aging and obesity

Barandier, Christine ; Montani, Jean-Pierre ; Yang, Zhihong

In: American Journal of Physiology - Heart & Circulatory Physiology, 2005, vol. 289, p. H1807-H1813

Adipocytes and perivascular adipose tissue are emerging as regulators of vascular function. The effects of adipocytes and perivascular adipose tissue on human smooth muscle cell (SMC) proliferation were investigated. Conditioned medium was prepared from cultured premature and differentiated 3T3-L1 adipocytes and from periaortic adipose tissue from young (3 mo) and old (24 mo) Wistar-Kyoto (WKY)...

Université de Fribourg

The direct effect of leptin on skeletal muscle thermogenesis is mediated by substrate cycling between de novo lipogenesis and lipid oxidation

Solinas, Giovanni ; Summermatter, Serge ; Mainieri, Davide ; Gubler, Marcel ; Pirola, Luciano ; Wymann, Matthias P. ; Rusconi, Sandro ; Montani, Jean-Pierre ; Seydoux, Josiane

In: FEBS Letters, 2004, vol. 577 (3), p. 539-544

We report here studies that integrate data of respiration rate from mouse skeletal muscle in response to leptin and pharmacological interference with intermediary metabolism, together with assays for phosphatidylinositol 3-kinase (PI3K) and AMP-activated protein kinase (AMPK). Our results suggest that the direct effect of leptin in stimulating thermogenesis in skeletal muscle is mediated by...

Université de Fribourg

Substrate cycling between de novo lipogenesis and lipid oxidation: a thermogenic mechanism against skeletal muscle lipotoxicity and glucolipotoxicity

Dulloo, Abdul G. ; Gubler, Marcel ; Montani, Jean-Pierre ; Seydoux, Josiane ; Solinas, Giovanni

In: International Journal of Obesity, 2004, vol. 28 (Suppl. 4), p. S29-S37

Life is a combustion, but how the major fuel substrates that sustain human life compete and interact with each other for combustion has been at the epicenter of research into the pathogenesis of insulin resistance ever since Randle proposed a 'glucose-fatty acid cycle' in 1963. Since then, several features of a mutual interaction that is characterized by both reciprocality and dependency between...

Université de Fribourg

Ectopic fat storage in heart, blood vessels and kidneys in the pathogenesis of cardiovascular diseases

Montani, Jean-Pierre ; Carroll, Joan F. ; Dwyer, Terry M. ; Antic, Vladan ; Yang, Zhihong ; Dulloo, Abdul G.

In: International Journal of Obesity, 2004, vol. 28, p. S58-65

In humans and most animal models, the development of obesity leads not only to increased fat depots in classical adipose tissue locations but also to significant lipid deposits within and around other tissues and organs, a phenomenon known as ectopic fat storage. The purpose of this review is to explore the possible locations of ectopic fat in key target-organs of cardiovascular control (heart,...

Université de Fribourg

Thrombin Stimulates Human Endothelial Arginase Enzymatic Activity via RhoA/ROCK Pathway

Ming, Xiu-Fen ; Barandier, Christine ; Viswambharan, Hema ; Kwak, Brenda R. ; Mach, François ; Mazzolai, Lucia ; Hayoz, Daniel ; Ruffieux, Jean ; Rusconi, Sandro ; Montani, Jean-Pierre ; Yang, Zhihong

In: Circulation, 2004, vol. 110, p. 3708-3714

Background— Arginase competes with endothelial nitric oxide synthase (eNOS) for the substrate L-arginine and decreases NO production. This study investigated regulatory mechanisms of arginase activity in endothelial cells and its role in atherosclerosis. Methods and Results— In human endothelial cells isolated from umbilical veins, thrombin concentration- and time-dependently stimulated...