Sex difference in peripheral arterial response to cold exposure
ABSTRACT In Japan, there is a symptom commonly referred to as "Hie-sho", which is a feeling of coldness or chill in a particular part of the body, and it can sometimes be unendurable. This phenomenon is known to occur more frequently in women. The present study used synchrotron radiation micro-angiography (SRMA) to examine the hypothesis that this feeling is derived from a sex difference in the vascular response to coldness.
The hind limb of male (Group M) and female (Group F) Wistar rats was exposed to cold and the tissue temperature was recorded. SRMA with a spatial resolution of 26 microm was used to measure arterial diameter. The reduction in temperature brought on by cold exposure was significantly larger in Group F than in Group M (p<0.05). SRMA showed that the arteries were dilated by cold exposure in both groups; however, the percentage dilatation in response was statistically small in Group F (69+/-40%) compared with Group M (118+/-73%) (p<0.05).
Arteries in the limbs of female rats did not expand as much as those of the males in response to cold exposure, which may explain why women feel the cold more than men.
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ABSTRACT: An urban-rural gap in stroke incidence or mortality has been reported. However, whether the effect of rurality on stroke is independent of the distribution of conventional individual-level risk factors and other community-level risk factors is inconclusive. A cohort study was conducted involving 4849 men and 7529 women residing in 12 communities throughout Japan. Baseline data were obtained between April 1992 and July 1995. Follow up was conducted annually to capture first-ever-in-life stroke events. During that period, geographic, demographic and weather information was obtained for each community. Multi-level logistic regression analysis was conducted to evaluate the association between stroke incidence and each geographic/demographic factor adjusted for meteorological parameters (temperature and rainfall), in addition to individual-level risk factors (age, body mass index, smoking, total cholesterol, hypertension, and diabetes). Throughout an average of 10.7 years' follow up, 229 men and 221 women with stroke events were identified. In women, low population (odds ratio [OR] per 1000 persons 0.97; 95% confidence interval 0.94-1.00), low population density (OR per 1/km2 0.85; 0.74-0.97) and high altitude (OR per 100 m 1.18; 1.09-1.28) increased the risk of stroke independently of individual-level risk factors; however, significance was absent for all three associations when further adjusted for weather parameters. Conversely, the association between each meteorological parameter and stroke in women was significant, even after adjustment for each of the three geographic/demographic factors. Similar results were obtained for cerebral infarction. The association between living in rural communities and stroke may be caused by the confounding effect of weather conditions in the communities studied.Rural and remote health 10(3):1493. · 0.87 Impact Factor
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ABSTRACT: Erythropoietin (Epo) is a hormone which regulates erythrocyte production. It has recently become known that Epo enhances angiogenesis. However, since shear stress is an initiator of arteriogenesis, this increase with Epo may be due to increased shear stress from erythrocytosis. To clarify this, we compared the effects of Epo on both angiogenesis and arteriogenesis. Myocardial infarction was induced by LAD ligation in Wistar rats (Epo, G-CSF and control). Epo (1,000 IU/kg) was administered immediately after ligation of the LAD. G-CSF was administered at 100 microg/kg/day for 5 days after the coronary ligation. Four weeks later, coronary angiography was performed using synchrotron radiation coronary micro-angiography with a Langendorff apparatus. The number of vessels was investigated by microscopy. The numbers of capillaries and arterioles (> 100 microm in diameter) were measured. Microscopical examination: Capillary density in the twilight zone was 95 +/- 19 in the control group, 126 +/- 24 in the G-CSF group, and 142 +/- 32 in the EPO group (control versus Epo: P < 0.005, control versus G-CSF: P < 0.05). Arteriole numbers were 4.3 +/- 0.2 in the control group, 6.9 +/- 1.0 in the G-CSF, and 11.8 +/- 0.6 in the Epo group (control versus Epo: P < 0.00001, G-CSF versus Epo: P < 0.00001, control versus G-CSF: P < 0.00001). The ratios of arterioles and capillaries were 0.048 +/- 0.013 in the control group, 0.057 +/- 0.016 in the G-CSF group, and 0.088 +/- 0.019 in the Epo group (control versus Epo: P < 0.0005, G-CSF versus Epo: P < 0.05). Angiography: The number of crossing arterioles in the 2 mm lattice was 5.4 +/- 1.7 in the Epo group and 3.8 +/-0.4 in the control group (P < 0.05). The gray scale values for the evaluation of capillaries was 128 +/- 3.7 and 119 +/- 2.1 in the Epo and control groups, respectively (P < 0.00005). Epo enhanced arterioles more significantly than it did capillaries in this infarcted rat heart model.International Heart Journal 11/2009; 50(6):801-10. DOI:10.1536/ihj.50.801 · 1.13 Impact Factor
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ABSTRACT: Although seasonal variation in stroke incidence has been reported, it is not known whether year-long exposure to particular meteorological conditions affects the risk of stroke independently of conventional cardiovascular risk factors. We conducted a cohort study involving 4849 men and 7529 women residing in 12 communities dispersed throughout Japan. Baseline data were obtained from April 1992 through July 1995. Follow-up was conducted annually to capture first-ever-in-life stroke events. Weather information during the period was also obtained for each community. Multilevel logistic regression analysis was conducted to evaluate the association between stroke incidence and each meteorological parameter adjusted for age, obesity, smoking status, total cholesterol, systolic blood pressure, diabetes, and other meteorological parameters. Over an average of 10.7 years of follow-up, 229 men and 221 women had stroke events. Among women, high annual rainfall (OR per 1000 mm, 1.46; 95% confidence interval, 1.05-2.03), low average ambient temperature (OR per 1 degrees C, 0.79; 0.66-0.94), and number of cold days per year (OR per 10 days, 3.37; 1.43-7.97) were associated with increased risk of stroke incidence, independent of conventional risk factors. Among men, number of cold days (OR per 10 days, 1.07; 1.02-1.12) was associated with an increased risk of stroke incidence, but the association became nonsignificant after adjustment for other risk factors. Similar results were obtained for cerebral infarction and cerebral hemorrhage. Long-term exposure to some meteorological conditions may affect the risk of stroke, particularly in women, independent of conventional risk factors.Journal of Epidemiology 03/2010; 20(2):136-42. DOI:10.2188/jea.JE20090103 · 2.86 Impact Factor