The Effects of Warm Water Bathing on Renal Function / 日本温泉気候物理医学会雑誌

ABSTRACT

The effects of the bathing on renal function were studied in 12 healthy men (32.3±7.7y. o.). The subjects took 41°C, 10min bathing and kept warm by a blanket for 30min, and then a mixture of 10% para-aminohippurate (PAH, 0.3<i>ml</i>/kg) and 10% sodium thiosulfate (NTS, 80<i>ml</i>) was infused intravenously. Clearance of PAH and NTS was calculated as the index of renal plasma flow (RPF) and glomerular filtration rate (GFR). PAH and NTS clearance test was also done at rest without bathing in another day. Blood Pressure (BP), Heart rate (HR), cardiac output (CO), sublingual temperature by electric thermista as deep body temperature were measured during the experiment. 30min after bathing, sublingual temperature was significantly increased by 0.9°C, and CO by +40%. After bathing, renal plasma flow (PAH clearance) significantly increased from 388.5±158.9<i>ml</i>/min to 572±170.7<i>ml</i>/min. Glomerular filtration rate (NTS clearance) was, however, unchanged from 115.6±37.3<i>ml</i>/min to 119.3±51.3<i>ml</i>/min. Filtration fraction (GFR/RPF) was significantly decreased. These results indicated that GFR was not improved by bathing although CO and RPF was increased by thermal vasodilation effect. The mechanism of unchanged GFR, despite of increased RPF, is probably that glomerular filtration pressure unchanged by thermal vasodilation of glomerular efferent and afferent arterioles.