Figure 3. Muscle membrane transporters.

The bars represent the mean density (n = 8, ±s.e.m.) of various membrane-bound transporter proteins. The values are calculated relative to the density in membrane samples obtained from lowlanders before the stay at altitude stay (sea level samples; white bars). Light grey bars: samples obtained after 2 weeks at altitude. Dark grey bars: samples obtained after 8 weeks at altitude. Black bars: samples from Bolivian natives. Abbreviations (from left to right): MCT1: monocarboxylate (lactate-H⁺) transporter 1. MCT4: monocarboxylate transporter 4. α1: Na⁺,K⁺-pump subunit α1. α2: Na⁺,K⁺-pump subunit α2. β1: Na⁺,K⁺-pump subunit β1. Na/H: Na⁺–H⁺ exchanger protein NHE1. NBC: Na⁺-HCO₃⁻ co-transporter. * Significantly different from sea-level values (P < 0.05).