The effects of heating on blood viscosity in vitro were investigated using a microcapillary viscometer developed in our laboratory. Blood samples extracted from six healthy male volunteers were incubated in a water bath at 37°C, 40°C, and 42°C for 15 and 60 minutes and then their viscosity was measured. These heating conditions had no influence on hematocrit, total protein, or fibrinogen. Although slight hemolysis was observed, it was not sufficient to influence hematocrit. Under the conditions described above, the viscosity of the incubated blood was about 90% of the control blood incubated at 25°C, with no differences among the three incubation temperatures. These findings may suggest that heating within physiological temperature range does not affect blood viscosity if hematocrit, total protein, and fibrinogen are constant.
Coefficients of variation were calculated for pulse rate (CV-PR) and blood pressure (CV-BP) under various respiratory conditions using a non-invasive method (the Finapres method), and the respiratory resonant phenomenon between pulse-rate variability and blood-pressure fluctuation was investigated. Subjects of this study included 148 healthy adults, 75 patients with diabetes mellitus (DM) and 64 patients with vibration syndrome (VS). During deep breathing of healthy adults in the sitting position, CV-PR was closely correlated with the coefficient of variation for diastolic blood pressure (CV-dBP) (R=0.75, p<0.01). Although CV-PR has been used as an index of autonomic nervous functions, it is strongly influenced by blood pressure and respiratory depth, so CV-PR itself is not suitable for investigating the present phenomena and seems to require correction. The corrected value (as obtained by dividing CV-PR by CV-dBP) in healthy adults during deep breathing in the sitting position was 1.05±0.21, extremely close to 1.0. This value decreased significantly with age (p<0.01) and was significantly lower (0.59+0.29) in the patients with DM than in healthy control adults (p<0.001). The value for the patients with VS was not significantly lower than that in the normal control adults. In the patients with VS and positive Raynaud's phenomenon, a significant decrease in value with age was noted (p<0.01), whereas the patients with VS and negative Raynaud's phenomenon showed no change in value with age. The coefficients of variation for pulse rate and blood pressure with their corrected values seemed to be useful as general indices of the sensitivity of several cardiovascular vagal reflexes including the baroreceptor reflex, which is probably involved in the present phenomenon. In addition, an examination of this phenomenon was found to be useful for determining the degree of complications in patients with DM and for assessing the peripheral circulatory function and therapeutic effects of balneotherapy on patients with VS.
A study was made on 15 healthy subjects to evaluate the efficacy of water immersion with commonly used raw materials on skin elasticity, viscoelasticity and hydration of stratum corneum. Samples used in this study included 30, 60, 90g of sodium hydrogen carbonate and 60g of bath preparation containing 90% in weight of sodium hydrogen carbonate (Cool Bathcrin®). These samples were dissolved into 200l of plain water kept at a temperature of 41°C. The duration of each bathing was 5min. Skin elasticity (skin distensibility), skin viscoelasticity and hydration of stratum corneum improved in all types of water immersion including plain water immersion. The skin distensibility, viscoelasticity and hydration state showed a statistically significant increase after water immersion with sodium hydrogen carbonate as compared with those before water immersion. In the plain water immersion group, no significant differences were observed between the values before and after water immersion with the exception of skin hydration. However, a significantly higher rate of increase in skin hydration was observed in the groups of water immersion with sodium hydrogen carbonate as compared with the plain water immersion. The above results show that alkaline salt, especially sodium hydrogen carbonate, improves skin distensibility, viscoelasticity, and hydration state. Furthermore, we recommend sodium hydrogen carbonate as one of the most useful components of bath preparation because it provides the suppleness, freshness, and smoothness of stratum corneum.