Significance of Rises in Urinary Bicarbonate Contents and pH Related with Increased Atmospheric Carbon Dioxide in Tokyo.

Abstract

Atmospheric carbon dioxide concentration was measured at several locations in Tokyo, for two weeks, in December, 1995 and 1996, and was found to be increased up to 550 ppm, while it was shown by us to be 450 ppm in December, 1994. These results demonstrate that atmospheric carbon dioxide is steadily increasing at faster rates in Tokyo than we expect, though it has been considered that the atmospheric carbon dioxide is still as much as 350 ppm. Bicarbonate concentration and pH of urine of 13 medical students in Tokyo were also measured for the same period in December of 1995 and 1996, and were found to be significantly increased compared with the values that were reported in the past. Furthermore, urinary bicarbonate and pH were extensively increased, when 4 and 5 students made 3-hour car trip in two different cars with all windows closed, where carbon dioxide was increased up to about 5000 ppm within 1 hour. These results support our previous hypothesis that the increase of atmospheric carbon dioxide may be reflected by the increase of urinary bicarbonate and pH. Our results also suggest that the environmental situation is being seriously aggravated in Tokyo, year by year, in terms of atmospheric carbon dioxide.

Significance of Post-Exercise Increment of Urinary Bicarbonate and pH in Subjects Loaded with Submaximal Cycling Exercise

“…The present results suggest that the measurement of urinary bicarbonate and urinary pH will be useful to evaluate the acid-base balance in subjects exposed to high concentrations of atmospheric CO2 (Tomoda et al 1995(Tomoda et al , 1997, or with increased amounts of endogeneous CO2 in the blood after heavy exercise such as submaximal cycling exercise.…”

“…Pitts et al (1949) indicated that the excretion of titrable acid into urine decreases according to the increase of discharged amounts of bicarbonate into the urine from the blood, which is consistent with the view that during hypercapnea, bicarbonate will accumulate in the blood, resulting in discharge of bicarbonate into the urine and leftover hydrogen ion in the blood; thereby, causing acute respiratory acidosis. In 1990, Tomoda et al (1995Tomoda et al ( , 1997 reported that a large amount of bicarbonate was discharged into the urine accompanying the urinary alkalization in subjects who were confined to enclosed rooms or cars with closed windows and who inspired higher concentrations of CO2 for 3 hours or so. This result was explained by the fact that the increased CO2 in the blood was converted to bicarbonate and hydrogen ion by erythrocytic carbonic anhydrase, and the excessively produced bicarbonate was discharged into the urine.…”

“…Since increased atmospheric CO2 influences the levels of urinary bicarbonate and pH in the human body (Tomoda et al 1995(Tomoda et al , 1997, the level of atmospheric CO2 in the room where the exercise study was performed was measured by a portable CO2 meter (Fuji Electronics Co., Ltd., Tokyo) at 9 : 30, 10 : 30, 11 : 30 and 12 : 30 on the days of exercise study. It was shown that the level of atmospheric CO2 in the room was almost constant (in the range between 650 ppm and 800 ppm).…”