Diameter and Elasticity of the Ascending Aorta during Infusion of Noradrenaline

Aars, Harald

doi:10.1111/j.1748-1716.1971.tb05059.x

Cited by 34 publications

(9 citation statements)

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“…Several lines of evidence from experimental studies suggest that changes in arterial smooth muscle activity, such as those produced by the autonomic nervous system, affect the dimensions as well as the stiffness of the arterial wall. 4 Gerova and Gero 5 have shown that electrical stimulation of the lumbar sympathetic nerves induces a significant reduction of the diameter of the femoral artery without changes in arterial pressure; similarly, norepinephrine produces a contraction of the aortic smooth muscle with a reduction in diameter. 6 In the same way, phenoxybenzamin abolishes the constrictive response to hemorrhage and causes an increase in aortic diameter.…”

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confidence: 99%

Effects of alpha 1-blockade on arterial compliance in normotensive and hypertensive rats.

1991

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The effects of blockade of cq-adrenergic receptors on the mechanical properties of the arterial wall were studied in 10 spontaneously hypertensive rats (SHR) as compared with 10 matched normotensive Wistar-Kyoto (WKY) rats. Ascending aortic pressure and flow were recorded in open-chest anesthetized rats, and the systemic arterial compliance was calculated. Intravenous injection (1 mg/kg) of Urapidil, a selective «,-adrenergic antagonist, induced a significant decrease in arterial pressure (-26%, p<0.01 and -37%, p<0.001 in WKY rats and SHR, respectively) without significant changes in cardiac output. In control conditions, systemic arterial compliance was lower in SHR (3.29 ±1.52 /il/mm Hg) than in WKY rats ( 4 J 5 ± U 5 fil/mm Hg, p<0.01). Urapidil injection induced significant increases in systemic arterial compliance values in both strains (p<0.001). In another set of experiments (15 WKY rats and 15 SHR), the carotid compliance (filjmm Hg) was determined from the arterial volumepressure relation under control conditions, after local incubation with Urapidil, and after total abolition of the vascular smooth muscle by KCN. In WKY rats, the carotid compliance increased markedly after incubation with Urapidil at doses corresponding to 1 mg/kg (+31%, p<0.01). A further increase in the carotid compliance was observed after KCN poisoning (+11%, p<0.05). In SHR, incubation with Urapidil at doses corresponding to 2 mg/kg were necessary to induce a significant increase in compliance (+38%). At this dosage, there was no further increase in compliance after KCN poisoning. The present study suggests that (^blockade influences the arterial compliance in normotensive and hypertensive rats independently of its effects on the arterial blood pressure. (Hypertension 1991;17:534-540)

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Effects of alpha 1-blockade on arterial compliance in normotensive and hypertensive rats.

1991

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“…In an investigation on the effects of noradrenaline on ascending aortic diameter, only small changes in diameter were observed. 31 While diameter changes were small (6%), changes to the dynamic stiffness of the ascending aorta due to the constriction were more meaningful,…”

Section: Sympathetic Effects On Arterial Stiffnessmentioning

confidence: 99%

P3.21 Conductance and Capacitance Effects of Acute, Electrical, Carotid Baroreflex Stimulation

Burgoyne

Tyberg

Belenkie

et al. 2012

ARTRES

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Baroreflex activation therapy (BAT) is effective in resistant hypertension; we hypothesized that BAT increases both venous capacitance and arterial conductance. We measured aortic pressure and flow and inferior vena caval flow and used a modified Brooksby-Donald technique to evaluate sub-diaphragmatic blood volume. Data were recorded with BAT, and with sodium nitroprusside (SNP) and Angiotensin II (Ang II) infusions, alone and with BAT.BAT substantially increased venous capacitance and arterial conductance. SNP also increased venous capacitance and arterial conductance. During SNP infusion BAT remained effective, further decreasing blood pressure and increasing capacitance and conductance. Ang II decreased both capacitance and conductance. During Ang II infusion, increased BAT reversed the decrease in venous capacitance while restoring BP completely and conductance to 80% of baseline.BAT decreases blood pressure and increases arterial conductance and venous capacitance, even when combined with powerful vasoactive drugs. These may be important effects in hypertension.iii Acknowledgements I would like to thank those who contributed directly to this thesis and my graduate studies experience, including Nigel Shrive, Israel Belenkie, and Jim Georgakopoulos. Nigel and Israel's experience and approachability, and Jim's knowledge and enthusiasm for research make them excellent collaborators. The relationship between the Tyberg lab and CVRx has provided insight into the challenges of medical device development, as well as access to unique research tools. The results in this thesis represent only a fraction of my experience gained as a graduate student in Biomedical Engineering. The lab's relationship with the Stephenson Cardiovascular MRI Centre, facilitated by Jacqueline McQuaker, represents one of many opportunities I've had to explore research beyond my own work. Working in the lab would not have been so successful and enjoyable without the company of my colleagues. Post-Doctoral fellows Jamie Mitchell and Chris Bouwmeester were good company and always generous with their knowledge. It has been a pleasure to share the chores and challenges of graduate work with fellow students Kristen Handkammer and LindsayBurrowes. Technical support from John Nystrom has always kept our excuses to a minimum.Not enough can be said in thanking my family. As with most of my endeavours, their support has facilitated my studies. While their support is never failing, I shall never take it for granted.Finally, I would like to thank the two constants of the Tyberg lab; Cheryl Meek and John Tyberg.Cheryl's technical expertise and surgical success have translated into greater and greater demands from us, which she typically meets with more success. Her collegial nature is likely the reason why nobody has the need to develop their conflict resolutions skills while working in her lab.To talk about John Tyberg as a supervisor, researcher, mentor, and friend, without repeating the accolades that every student before has spoken of him would be impos...

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“…This is most commonly achieved with a high‐frequency ultrasound transducer working in wall‐tracking mode to measure the displacement of the near and far arterial walls during the cardiac cycle (Hoeks et al ., 1985; Kawasaki et al ., 1987; Mooser et al ., 1988; Gustafsson et al ., 1989; Hirai et al ., 1989; Lânne et al ., 1992a,b; Sonesson et al ., 1993; Hansen et al ., 1995). Alternatively, the ultrasonic transit‐time method (the so‐called sonomicrometry method) used in animal experiments requires ultrasonic transducer placed on each side of the artery (Aars, 1971; Hartley et al ., 1978; Pagani et al ., 1978; Tomoike et al ., 1981; Vatner et al ., 1985; Gentile et al ., 1988; Hirooka et al ., 1988; Barra et al ., 1993; White et al ., 1994; Armentano et al ., 1995; Rolland et al ., 1999). It has been shown that the surgical approach required to place the transducers may induce acute changes in wall mechanics (Megerman et al ., 1986) and late post‐operative fibrosis (Hasson et al ., 1984; Greisler et al ., 1992), so that repeated measurements may be difficult, even in experimental studies on animals.…”

Section: Introductionmentioning

confidence: 99%

Validation of a newly developed B‐mode image‐processing technique versus wall‐tracking ultrasound for the study of wall mechanics in small‐calibre arteries

Vernhet¹,

Demaria²,

Juan³

et al. 2002

Clin Physio Funct Imaging

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Diameter and Elasticity of the Ascending Aorta during Infusion of Noradrenaline

Cited by 34 publications

References 9 publications

Effects of alpha 1-blockade on arterial compliance in normotensive and hypertensive rats.

Effects of alpha 1-blockade on arterial compliance in normotensive and hypertensive rats.

P3.21 Conductance and Capacitance Effects of Acute, Electrical, Carotid Baroreflex Stimulation

Validation of a newly developed B‐mode image‐processing technique versus wall‐tracking ultrasound for the study of wall mechanics in small‐calibre arteries

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