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Good vibrations and strong bones?
Jens Jordan
288:555-556, 2005. doi:10.1152/ajpregu.00799.2004 Am J Physiol Regulatory Integrative Comp Physiol You might find this additional information useful.
This article cites 11 articles, 4 of which you can access free at: Medline items on this article's topics on the following topics: Physiology . Blood Circulation Physiology . Bone Physiology . Bone Development Physiology . Bone Mineral Density Medicine . Cholesterol Medicine . Menopause Updated information and services including high-resolution figures, can be found at: American Journal of Physiology - Regulatory, Integrative
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illuminate normal or abnormal regulation and integration of physiological mechanisms at all levels of biological organization,
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Am J Physiol Regul Integr Comp Physiol 288: R555–R556, 2005;doi:10.1152/ajpregu.00799.2004.
Editorial Focus
Jens Jordan
Franz-Volhard Clinical Research Center, Charite´, Campus Buch and HELIOS Klinikum, Berlin, Germany THE HUMAN PHYSIOLOGY of bone perfusion has been neglected.
bone vascular function. In this study (1), oophorectomy in- The issue may be explained in part by technical difficulties in creased the responsiveness of isolated vascular rings from assessing bone blood flow in vivo. Currently available tech- small bone arteries to norepinephrine and to endothelin. How- niques may be rather expensive, and the access of interested ever, whether vascular damage to the bone vasculature ex- scientists to these techniques may be limited. Another possible plains the association between osteoporosis and cardiovascular explanation for the neglect is the fact that the integration between cardiovascular and bone research fails because each Interestingly, treatment of some cardiovascular risk factors research area is narrowly focused on its own organ or tissue appears to have a beneficial effect on osteoporosis. For exam- system. This state of affairs is unfortunate given the potentially ple, smoking cessation leads to an improvement in markers of important interactions between the cardiovascular system and bone turnover within a 6-wk period (5). Lipid-lowering therapy bone. Indeed, bone and vascular disease frequently coexist in increases bone mineral density (3). Thiazide diuretics appear to the same patients. Osteoporosis risk is increased in patients lower the bone fracture rate (7). Moreover, beta blockers with atherosclerosis and vice versa. The correlation is probably appear to do the same (6). Finally, estrogen replacement explained in part by a common underlying mechanism rather therapy improves bone density and endothelial function in than a spurious association. Bone perfusion may be such a If bone perfusion has an important effect on bone density, could Perfusion appears to be matched to the metabolic demands an increase in bone perfusion also increase bone density? How of the bone. For example, increased bone turnover and inflam- can bone blood flow be increased? In this issue of the American mation are associated with an increased blood flow. Blood flow Journal of Physiology-Regulatory, Integrative and Comparative decreases as bone turnover normalizes or the inflammation has Physiology, Stewart et al. (9) reviewed the literature on bone resolved. Failure of the vasculature to respond to metabolic perfusion and bone mass. The few available publications seem to needs of the bone might predispose to bone disease. Alterations suggest that increased venous pressure and increased perfusion in vascular function and in intraosseous angiogenesis may be tend to increase bone mass. They reasoned that an increase in leg contributory. Several studies suggest a correlation between and, perhaps, bone perfusion may contribute to the recently bone perfusion and bone density. Studies used different meth- described increase in bone mass with whole body vibration (10).
To address this issue, they assessed changes in leg hemodynamics odologies and are, therefore, difficult to compare. In one study and fluid shifts using strain-gauge and impedance plethysmogra- (8), magnetic resonance imaging was used to obtain an indirect phy before and during whole body vibration. The vibration was measure of bone marrow perfusion at the level of the lumbar elicited by placing the subjects on a vibrating platform. Whole spine. Bone marrow perfusion was correlated with bone min- body vibration increased blood flow to the lower body while eral density in postmenopausal but not in premenopausal subjects were in the supine position. Furthermore, the intervention women. In another study (2), decreased bone marrow perfusion reversed the decrease in leg blood flow in the upright position.
was associated with progression of collapse of fractured ver- Finally, leg vibration shifted the microvascular filtration relation tebra in patients with osteoporosis.
to higher pressures, both in the supine and in the upright position.
Perhaps “bone vascular disease” contributes to osteoporosis.
The shift is probably explained by improved lymphatic drainage.
One might further speculate that interventions that improve Thus whole body vibration substantially altered leg hemody- bone vascular function may have a beneficial effect on bone structure. The anatomic structure of blood small blood vessels The study by Stewart et al. (9) necessarily has some limita- within the bone is similar to the structure of blood vessels in tions. The authors did not measure bone perfusion directly. It other tissues. These vessels may be susceptible to the same is difficult to know whether the change in leg blood flow is genetic and environmental risk factors.
associated with a change in bone perfusion. I would suggest If bone vascular disease and, thus, alterations in perfusion comparing “cheap” leg blood flow measurements with “costly” were a cause of excessive bone loss, atherosclerosis risk factors more direct measurements of bone blood flow in future studies.
should also increase the risk for osteoporosis. Indeed, smoking, It would be tremendously helpful to have inexpensive methods diabetes mellitus, elevated low-density lipoprotein cholesterol, that could be used to obtain hemodynamic measurements that reduced high-density lipoprotein cholesterol, and hyperhomo- are relevant for bone hemodynamics. Furthermore, the authors cystinemia are associated with increased cardiovascular risk did not provide data linking changes in hemodynamics and and reduced bone mineral density(4). Both the risk for cardio- bone turnover. Perhaps more questions were raised than an- vascular disease and the risk for osteoporosis increase sharply swered. Nevertheless, the study is of importance because it after menopause. A study in rabbits suggests that experimental may generate interest in studying the interaction between bone “postmenopause” through oophorectomy leads to changes in and the cardiovascular system. Promising clinical and epide-miological data linking vascular disease and osteoporosisought to be supported by solid physiological work. Equally Address for reprint requests and other correspondence: J. Jordan, Franz- important, the study suggests that even in the era of molecular Volhard Clinical Research Center, Haus 129, Charite´-Campus Buch, Wiltberg-str. 50, 13125 Berlin, Germany (E-mail: [email protected]).
medicine, a simple and “old-fashioned” physiological method 0363-6119/05 $8.00 Copyright 2005 the American Physiological Society Editorial Focus
is still useful to raise new scientific hypotheses. A final ques- 5. Oncken C, Prestwood K, Cooney JL, Unson C, Fall P, Kulldorff M,
tion for those who will not be interested in bones: Do good and Raisz LG. Effects of smoking cessation or reduction on hormone
profiles and bone turnover in postmenopausal women. Nicotine Tob Res 4:
vibrations add to angiogenesis elsewhere? 6. Schlienger RG, Kraenzlin ME, Jick SS, and Meier CR. Use of
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AJP-Regul Integr Comp Physiol • VOL 288 • MARCH 2005 • www.ajpregu.org

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