Carbonic anhydrase inhibition delays plasma lactate appearance with no effect on ventilatory threshold Article (Web of Science)

abstract

  • The effect of carbonic anhydrase (CA) inhibition with acetazolamide (Acz, 10 mg/kg body wt iv) on exercise performance and the ventilatory (V˙eT) and lactate (LaT) thresholds was studied in seven men during ramp exercise (25 W/min) to exhaustion. Breath-by-breath measurements of gas exchange were obtained. Arterialized venous blood was sampled from a dorsal hand vein and analyzed for plasma pH,[Formula: see text], and lactate concentration ([La−]pl).V˙eT [expressed as O2 uptake (V˙o 2), ml/min] was determined using the V-slope method. LaT (expressed asV˙o 2, ml/min) was determined from the work rate (WR) at which [La−]plincreased 1.0 mM above rest levels. Peak WR was higher in control (Con) than in Acz sutdies [339 ± 14 vs. 315 ± 14 (SE) W]. Submaximal exercise V˙o 2 was similar in Acz and Con; the lowerV˙o 2 at exhaustion in Acz than in Con (3.824 ± 0.150 vs. 4.283 ± 0.148 l/min) was appropriate for the lower WR. CO2output (V˙co 2) was lower in Acz than in Con at exercise intensities ≥125 W and at exhaustion (4.375 ± 0.158 vs. 5.235 ± 0.148 l/min). [La−]plwas lower in Acz than in Con during submaximal exercise ≥150 W and at exhaustion (7.5 ± 1.1 vs. 11.5 ± 1.1 mmol/l).V˙eT was similar in Acz and Con (2.483 ± 0.086 and 2.362 ± 0.110 l/min, respectively), whereas the LaT occurred at a higherV˙o 2 in Acz than in Con (2.738 ± 0.223 vs. 2.190 ± 0.235 l/min). CA inhibition with Acz is associated with impaired elimination of CO2 during the non-steady-state condition of ramp exercise. The similarity inV˙eT in Con and Acz suggests that La−production is similar between conditions but La− appearance in plasma is reduced and/or La− uptake by other tissues is enhanced after the Acz treatment.

authors

publication date

  • 2000

webpage

published in

number of pages

  • 8

start page

  • 713

end page

  • 721

volume

  • 88

issue

  • 2