RELATIONSHIP BETWEEN MAXIMAL PULMONARY VENTILATION AND ARTERIALIZED VENOUS-BLOOD POTASSIUM AND DOPAMINE CONCENTRATIONS OBTAINED AT EXHAUSTION IN MAN

This study was performed to test the hypothesis that potassium concent ration in arterialized blood may be closely related to maximal pulmona ry ventilation (VEmax) Obtained at exhaustion during maximal exercise in man. Eleven healthy men performed bicycle exercise with incremental loading at 60 rpm until exhaustion. Pulmonary ventilation (VE), oxyge n uptake (VO2), and heart rate (HR) were determined continuously throu ghout the experiment. Arterialized venous blood samples were collected to measure potassium ([K+]), lactate ([La]), hydrogen ion (pH), catec holamine ([CAI), and dopamine ([DA]) concentrations. A significant cor relation (r=0.98-0.88) between VE and [K+], [La], and pH during exerci se was observed in all subjects. Furthermore, a close relationship was found in this study between dopamine concentration measured at exhaus tion ([DA](0)) and maximal pulmonary ventilation per kilogram of body weight (VEmax/W) (r=-0.668, p<0.05) or maximum oxygen uptake per kilog ram of body weight (VO(2)max/W) (r=0.720, p<0.05). However, no signifi cant correlation was found between VEmax/W and [K+](0) (r=0.202, NS), [La](0) (r=-0.096, NS), and pH(0) (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.