2008 Volume 72 Issue 8 Pages 1367-1372
Background 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. Methods and Results 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 μm 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). Conclusion 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. (Circ J 2008; 72: 1367 - 1372)
