Effect of hypercapnia on changes in blood pH, plasma lactate and ammonia due to exercise

Abstract

The present study examined the effects of hypercapnia on changes in blood pH, plasma lactate and ammonia due to exhaustive exercise. Six male subjects underwent exercise of increasing intensity until exhaustion: (1) breathing air = MAX (maximal exercise), or (2) under hypercapnia (HC: 21% O 2 , 6% CO 2 ) that had been maintained from 60 min before to 30 min after exercise = HC; and (3) exercise of the same intensity as HC in air = SUB (submaximal exercise). Arterialized blood was drawn from a superficial vein. Blood pH in HC was significantly lower than in MAX or SUB at rest, at the end of exercise and throughout recovery (P<0.05). Plasma lactate and ammonia concentration in HC was significantly lower than in MAX (P<0.05), and similar to that in SUB at the end of exercise and throughout recovery. Respiratory acidosis resulting from hypercapnia shifted the linear lactate to blood pH relationship during exhaustive exercise below that at normocapnia (P<0.001). The reduced slope of linear blood pH to ammonia relationship under hypercapnia (P<0.001) is attributed to lactic acidosis that is less, due to the lesser work intensity at the end of exhaustion, than that of normocapnia. From these results we conclude that (1) hypercapnia-induced respiratory acidosis promoted the decrease in blood pH due to lactate production throughout recovery; (2) plasma lactate concentration at maximal exercise was lowered under hypercapnia; (3) plasma ammonia concentration at maximal exercise was reduced, probably due to a less intense lactic acidosis.

Circulatory and Respiratory Response to Exercise With Added Respiratory Dead Space

“…the parameter did not reach the sta tistical significance. This result is in accordance with those obtained by researchers studying the effects of hypercapnic gas inhalation (Graham et al [21], Kato et al [19]). In the experiment of the latter, at the end of the exercise per formed in hypercapnia HR was not significantly diffe rent from the same exercise performed without hyper capnia.…”

“…According to their findings, an increase in CO 2 leads to environmental acidosis, thereby inhibiting phosphofructokinase (PKF) and glycolysis (Hollidge-Horvat et al [20], Kato et al [19]). Furthermore, they report that during exercise the blood lactate level under hypercapnia is lower than un der normocapnia (Graham et al [21,22], Kato et al [19]). …”

“…the increased blood partial pressure of cO 2 results from the suppressed diffusion of cO 2 to alveoli. It occurs on account of increased cO 2 in the tube and alveoli, thereby decreasing the cO 2 pressure gradient between [19]). this is caused by carbonic acid disso ciation, synthesized from carbon dioxide and water.…”

The Measurement of Ammonia in Human Breath and its Potential in Clinical Diagnostics

“…This can cause an increase in lactate and ammonia in blood (Broomfield and Grunewald, 2012). During maximal exercise, ammonia and lactate levels decrease because of a reduction in blood pH caused by hypercapnia due to respiratory acidosis (Kato et al, 2005). Since ammonia is pH-dependent, breath testing can be linked to protein metabolism and changes of blood pH under exercise (Schubert et al, 2012).…”

Effect of Hypercapnic Severity on Plasma Ammonia Accumulation and Respiratory Exchange Ratio during Incremental Exercise

“…A decrease in blood La concentration during exercise under hypercapnic conditions was previously reported [1][2][3][4], and La threshold (LT) was unchanged by hypercapnia [4]. Further, we reported that plasma Am concentration was reduced at maximal exercise in a 6% inhaled CO 2 condition [5]. However, the changes in Am dynamics during exercise, including Am threshold (AmT), remain unknown since blood samples were drawn following exercise.…”