| 1. |
- Gan, Li-Ming, 1969, et al.
(författare)
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A short period of apnoea causes a marked increase in coronary flow velocity: a transthoracic pulsed wave Doppler study.
- 2005
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Ingår i: Clinical physiology and functional imaging. - 1475-0961. ; 25:3, s. 148-51
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Tidskriftsartikel (refereegranskat)abstract
- Coronary artery flow velocity during a short period of apnoea was investigated by transthoracic Doppler recording in 10 healthy men, aged 24-52. During breath holding for 29 +/- 6 s the oxygen saturation in the finger, measured by pulse oxymetry, decreased from 97.5 +/- 0.8 to 90.0 +/- 3.2% (P < 0.001). The maximal coronary blood flow velocity in the left anterior descending artery increased by 62% from 0.26 +/- 0.09 to 0.42 +/- 0.10 m s(-1) and the mean diastolic flow velocity by 47% from 0.19 +/- 0.04 to 0.28 +/- 0.08 m s(-1) (P < 0.001). In most subjects the increase of velocity started already after a few seconds of apnoea. Besides theoretical implications the results show that it is very important to be aware of the higher velocity during apnoea in order to avoid misinterpretation when using breath holding during magnetic resonance imaging or Doppler recording of coronary flow.
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| 2. |
- Hägg Samuelsson, Ulrika, 1973
(författare)
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Effects of physical exercise on coronary and peripheral vascular function. An integrative physiological study from rat to man
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physical exercise is beneficial for the cardiovascular health. Numerous epidemiological studies reveal that physical activity reduces the risk of cardiovascular related death. Nevertheless, the underlying vessel wall specific physiological and molecular mechanisms still remain incompletely understood. The aim of this thesis was to investigate coronary and peripheral vascular function as a consequence of exercise and a physically active lifestyle. A wheel-cage model for voluntary running in spontaneously hypertensive rats was used to mimic the human exercise situation. Endothelial function in conduit and resistance arteries was investigated using myograph techniques. Vascular stiffness was studied in vivo, using tissue Doppler imaging, and ex vivo, using a perfusion chamber and ultrasound biomicroscopy. High-frequency echocardiography was used to assess cardiac function and coronary flow velocity reserve (CFVR) in the left anterior descending coronary artery. A broad-base gene expression microarray analysis of aortic tissue was performed, and gene expressions of endothelial nitric oxide synthase (eNOS), copper zinc superoxide dismutase (CuZnSOD) and heat shock proteins 60 and 70 (HSP60 and HSP70) were validated with real-time PCR. Young healthy adults were submitted to studies of flow-mediated vasodilation (FMD), intima-media thickness (IMT), arterial wall stiffness index (SI), echocardiographic examination, CFVR measurements and sub-maximal exercise capacity (VO2maxc). We found that CFVR, resistance artery endothelial function and aortic compliance are improved after exercise in rats. Microarray analysis revealed a concerted down-regulation of HSP genes. After training, aortic and cardiac CuZnSOD gene expression was upregulated, while eNOS remained unchanged. In man, VO2maxc was positively correlated to CFVR and negatively correlated to IMT and SI. FMD was increased in subjects with high compared to moderate VO2maxc. Subjects with high CFVR had high ratios between endothelial-dependent and independent vasodilation in the forearm and low SI. We conclude that a physically active life-style is beneficial for coronary and peripheral artery function in young adults. Aerobic exercise is responsible for the exercise-induced cardiovascular effects, which are independent of blood lipids, in a young population. Also, exercise-induced upregulation of antioxidative enzymes might be a key mechanism underlying peripheral and coronary artery function. HSP might play a role in exercise-induced beneficial vascular effects. Finally, the established methodological platform may facilitate translational physiological studies from animal to man.
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| 3. |
- Hägg Samuelsson, Ulrika, 1973, et al.
(författare)
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Gene expression profile and aortic vessel distensibility in voluntarily exercised spontaneously hypertensive rats: potential role of heat shock proteins
- 2005
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Ingår i: Physiol Genomics. - 1531-2267 .- 1094-8341. ; 22:3, s. 319-26
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Tidskriftsartikel (refereegranskat)abstract
- Physical exercise is considered to be beneficial for cardiovascular health. Nevertheless, the underlying specific molecular mechanisms still remain unexplored. In this study, we aimed to investigate the effects of voluntary exercise on vascular mechanical properties and gene regulation patterns in spontaneously hypertensive rats. By using ultrasound biomicroscopy in an ex vivo perfusion chamber, we studied the distensibility of the thoracic aorta. Furthermore, exercise-induced gene regulation was studied in aortae, using microarray analysis and validated with real-time PCR. We found that distensibility was significantly improved in aortas from exercising compared with control rats (P < 0.0001). Exercising rats demonstrated a striking pattern of coordinated downregulation of genes belonging to the heat shock protein family. In conclusion, voluntary exercise leads to improved vessel wall distensibility and reduced gene expression of heat shock protein 60 and 70, which may indicate decreased oxidative stress in the aortic vascular wall.
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| 4. |
- Hägg Samuelsson, Ulrika, 1973, et al.
(författare)
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Physical exercise capacity is associated with coronary and peripheral vascular function in healthy young adults.
- 2005
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Ingår i: American journal of physiology. Heart and circulatory physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 289:4, s. H1627-34
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Tidskriftsartikel (refereegranskat)abstract
- Short-term exercise training has been shown to improve cardiovascular function, whereas long-term effects of a physically active lifestyle, on coronary artery function in particular, are still not well studied. We explored possible relationships between physical exercise capacity and coronary and peripheral vascular function in healthy young adults. Twenty-nine healthy young male and female volunteers participated in the study. They underwent 1) basic clinical and echocardiographic characterization, 2) coronary flow velocity reserve (CFVR) measurement of the left anterior descending coronary artery (LAD), 3) common carotid artery (CCA) intima-media thickness (IMT) measurement, 4) assessment of CCA stiffness index (SI), 5) forearm flow-mediated vasodilation (FMD), and 6) submaximal exercise test. The calculated weight-adjusted maximal oxygen uptake capacity (Vo(2 max)(c)) was positively correlated to LAD CFVR and inversely correlated to IMT and SI. Also, subjects with high compared with moderate exercise capacity had higher FMD. In addition, subjects with LAD CFVR in the upper median had greater ratios between endothelium-dependent and -independent vasodilation in the forearm and lower SI in CCA. High exercise capacity due to a physically active lifestyle is associated with high coronary and peripheral artery function, indicating an early protective role of physical exercise for cardiovascular health.
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| 5. |
- Hägg Samuelsson, Ulrika, 1973, et al.
(författare)
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Voluntary physical exercise and coronary flow velocity reserve: a transthoracic colour Doppler echocardiography study in spontaneously hypertensive rats
- 2005
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Ingår i: Clin Sci (Lond). - 0143-5221. ; 109:3, s. 325-34
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we have developed and demonstrated a coronary artery imaging protocol in rats using transthoracic high-frequency CDE (colour Doppler echocardiography) to investigate the potential direct effects of exercise on CFVR (coronary flow velocity reserve). SHR (spontaneously hypertensive rats) performed voluntary exercise for 6 weeks. Rats were then submitted to ultrasonographic examination and CFVR measurements. The LAD (left anterior descending coronary artery) was visualized using transthoracic CDE in a modified parasternal long-axis view. Doppler measurement was made in mid-LAD during baseline and adenosine-induced hyperaemic condition. Gene and protein expression in cardiac tissue were studied using real-time PCR and immunohistochemistry. Adenosine infusion significantly (P<0.001, as determined by ANOVA) decreased HR, without affecting blood pressure in anaesthetized SHR. A significantly greater adenosine dose-dependent response was seen in exercised rats compared with controls (P=0.02, as determined by ANOVA). The baseline flow velocity in mid-LAD was 0.33+/-0.06 and 0.41+/-0.14 m/s in the exercised and control animals respectively (P value was not significant). The maximum adenosine-induced response was reached at a dose of 140 microg.kg-1 of body weight.min-1, and CFVR averaged at 2.6+/-0.53 and 1.5+/-0.24 in exercised and control animals respectively (P<0.01). Gene expression of CuZnSOD was up-regulated by 21% in exercised animals compared with controls (1.1+/-0.16 compared with 0.89+/-0.09; P<0.01), whereas eNOS expression was unchanged. In conclusion, CFVR in rats can be non-invasively assessed using CDE with high feasibility. Physical exercise is associated with improved CFVR and antioxidative capacity in SHR.
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| 6. |
- Johansson, Maria E, 1977, et al.
(författare)
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Haemodynamically significant plaque formation and regional endothelial dysfunction in cholesterol-fed ApoE-/- mice
- 2005
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Ingår i: Clinical Science. - 0143-5221 .- 1470-8736. ; 108:6, s. 531-8
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Tidskriftsartikel (refereegranskat)abstract
- Flow-mediated vasodilation is suggested as one of the mechanisms involved in arterial expansive remodelling, which is thought to be a defence mechanism in atherogenesis. In the present study, we tested the hypothesis that lumen obstructive plaque formation is associated with failure of NO (nitric oxide)-dependent vasodilation in conduit vessels. Cardiac function and aortic root flow velocities were assessed using high-resolution echocardiography and two-dimensional-guided pulsed Doppler in ApoE(-/-) (apolipoprotein E-deficient) mice fed a standard or high-cholesterol diet. Endothelial function in the proximal and mid-descending aortic regions was studied using a myograph technique. Flow velocity at the aortic root of cholesterol-fed ApoE(-/-) mice was significantly increased as a result of lumen narrowing, detected via histological analysis. NO-dependent vasodilatory responses were selectively impaired in the atherosclerosis-prone vascular regions in cholesterol-fed ApoE(-/-) mice. In conclusion, consumption of a high-cholesterol diet results in lumen obstructive plaque formation in ApoE(-/-) mice, which significantly alters aortic root haemodynamics. This phenomenon is associated with impaired NO-dependent vasodilation in vessel segments known to be prone to atherosclerosis.
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