Relationship between Maximal Pulmonary Ventilation and Arterialized Venous Blood Potassium and Dopamine Concentrations Obtained at Exhaustion in Man.

Abstract

This study was performed to test the hypothesis that potassium concentration in arterialized blood may be closely related to maximal pulmonary ventilation (V.Emax) obtained at exhaustion during maximal exercise in man. Eleven healthy men performed bicycle exercise with incremental loading at 60 rpm until exhaustion. Pulmonary ventilation (V.E), oxygen uptake (V.O2), and heart rate (HR) were determined continuously throughout the experiment. Arterialized venous blood samples were collected to measure potassium ([K+]), lactate ([La]), hydrogen ion (pH), catecholamine ([CA]), and dopamine ([DA]) concentrations. A significant correlation (r = 0.98-0.88) between V.E and [K+], [La], and pH during exercise was observed in all subjects. Furthermore, a close relationship was found in this study between dopamine concentration measured at exhaustion ([DA]0) and maximal pulmonary ventilation per kilogram of body weight (V.Emax/W) (r = -0.668, p < 0.05) or maximum oxygen uptake per kilogram of body weight (VO2MAX/W) (r = 0.720, p < 0.05). However, no significant correlation was found between V. Emax/W and [K+]0 (r = 0.202, NS), [La]0 (r = -0.096, NS), and pH0 (r = 0.344, NS). These results suggest that dopamine may play a more important role in the determination of maximal pulmonary ventilation during exercise in man than K+ or pH.

Effect of hypohydration on hyperthermic hyperpnea and cutaneous vasodilation during exercise in men

“…1) The effects of these factors may be too small to change ventilation. Indeed, changes in plasma K ϩ , pH, and catecholamines under conditions of dehydration (22,23,24) were smaller than those at high-intensity exercise (9,24,33). Further, increased chemosensory discharge was previously seen with a 10% increase in P osm (31,49), which is higher than that in the present study (ϳ2.5%); 2) factors 1 and 2 might balance factor 3, so that ventilation is not changed; 3) these factors have little or no effect on the ventilatory response.…”

“…Further, increased chemosensory discharge was previously seen with a 10% increase in P osm (31,49), which is higher than that in the present study (ϳ2.5%); 2) factors 1 and 2 might balance factor 3, so that ventilation is not changed; 3) these factors have little or no effect on the ventilatory response. Indeed, plasma K ϩ , pH, and catecholamine levels are not closely related to the increase in ventilation during exercise (9,33). When plasma K ϩ increases, peripheral chemoreceptors are excited and ventilation increases, and ventilatory responses to elevations in lactate acid and norepinephrine are enhanced (39).…”

Cardiopulmonary, blood metabolite and rating of perceived exertion responses to constant exercises performed at different intensities until exhaustion

“…The greater increase in plasma potassium and BLC during the TW 25% bout might have provided an additional stimulus for the cardiopulmonary system, increasing the VE and RR responses 18–20. Nevertheless, as the overall physiological steady state was observed during TW 25% , it is difficult to understand how metabolite accumulation and increased cardiopulmonary responses could be associated with the exercise termination at this exercise intensity.…”