EFFECTS OF 10-PPM HYDROGEN-SULFIDE INHALATION IN EXERCISING MEN AND WOMEN - CARDIOVASCULAR, METABOLIC, AND BIOCHEMICAL RESPONSES

This study examined the acute effects of 10-ppm hydrogen sulfide (H2S) inhalation, a concentration equal to its occupational exposure limit, on the cardiovascular, metabolic, and biochemical responses in health y volunteers. Fifteen men and 13 women completed two 30-minute exercis e sessions at 50% of their maximal oxygen uptake, during which they in haled medical air or 10 ppm H2S in a blind manner. Arterial and finger -prick blood samples were obtained before and during the final minute of exercise. Muscle biopsies were withdrawn from the right vastus late ralis immediately after exercise. Cardiorespiratory measurements were monitored using an automated metabolic cart interfaced with an electro cardiogram and blood pressure apparatus. A significant decrease in oxy gen uptake (VO2), with a concomitant increase in blood lactate, was ob served in men and women as a result of H2S exposure. No significant ch anges were observed in arterial blood parameters and the cardiovascula r responses under these conditions. Muscle lactate, as well as the act ivities of lactate dehydrogenase, citrate synthase, and cytochrome oxi dase, were not significantly altered by H2S exposure. However, there w as a tendency for muscle lactate to increase and citrate synthase acti vity to decrease in both genders in the presence of H2S. It appeared t hat 10-ppm H2S inhalation reduced VO2 during exercise, most likely by inhibiting the aerobic capacity of the exercising muscle. These findin gs question the scientific validity of the current occupational exposu re limit for H2S.