Table 2. Estimate of maximum rate of SR... | Rockefeller University Press

Table 2.

Estimate of maximum rate of SR Ca²⁺ pumping in intact fast-twitch human muscle fibers

Variable	Value
Isometric ATP turnover^{^a}	2,333 μM s⁻¹
Fraction of ATP turnover by Ca pump^{^b}	0.35
ATP turnover for Ca pumping at 37°C	817 μM s⁻¹
ATP turnover for Ca pumping at 25°C^{^c}	355 μM s⁻¹
Maximum rate of Ca uptake at 25°C^{^d}	711 μM s⁻¹

Variable	Value
Isometric ATP turnover^{^a}	2,333 μM s⁻¹
Fraction of ATP turnover by Ca pump^{^b}	0.35
ATP turnover for Ca pumping at 37°C	817 μM s⁻¹
ATP turnover for Ca pumping at 25°C^{^c}	355 μM s⁻¹
Maximum rate of Ca uptake at 25°C^{^d}	711 μM s⁻¹

Expressed relative to myoplasmic H₂O volume; converted from 140 mM min⁻¹ in sustained maximal contraction at 37°C (for details, see Barclay, 2017).

From data for type 2A human fibers (Szentesi et al., 2001) and other mammalian muscles (Barclay et al., 2007).

Assumed Q₁₀ = 2 (Barclay, 2012).

Two Ca²⁺ translocated for each ATP-splitting cycle (Weber et al., 1966).