Effects of Hot-spring Bathing on Blood Pressure and Lipoperoxides during the Aging Process in Spontaneously Hypertensive Rats / 日本温泉気候物理医学会雑誌

ABSTRACT

To find the effects of habitual hot-spring bathing from a young age on the blood pressure of adults, the effects of hot-spring bathing on lowering blood pressure and serum lipoperoxides were investigated using spontaneously hypertensive rats (SHR). Male SHRs, six week old, were subjected to hot bathing at 40°C for 10min per day for 14 weeks continuously.<br>1) Hot bathing tended to suppress blood pressure. For hot-spring bathing, blood pressure was maintained within 100 to 120mmHg until the end of the bathing experiment. Furthermore, these controlled values of blood pressure were maintained for more than 5 weeks after cessation of the experiment. For plain-water bathing, blood pressure increased gradually, but then was maintained within 100 to 145mmHg until the end of the experiment. These values were maintained for 4 weeks after cessation of the bathing experiment. In those SHRs that were not subjected to bathing, blood pressure was 100mmHg at the age of 6 weeks, 150mmHg at the age of 13 weeks, 160mmHg at the age of 19 weeks, and 170mmHg at the age of 24 weeks. Accordingly, it was found that hot-spring bathing is more effective than plain-water ordinary bathing in suppressing blood pressure.<br>2) The serum lipoperoxide values decreased during the 12th week of the bathing experiment. These values remained at a significantly low level until the end of the 6th week after cessation of the bathing experiment. This finding seems to suggest that habitual bathing from a young age may slow down the aging process.<br>3) It was shown that the concentrations of catecholamines in blood were lower in both the hot-spring bathing group and the plain-water bathing group than those in the non-bathing group. This may indicate that controlled secretion of catecholamines is related to the relaxation induced by bathing.<br>4) The rate of weight increase was significantly lower in the groups of SHRs subjected to hot-spring bathing and plain-water bathing from a young age than in the non-bathing group.