Fig. 4
a Transcellular active calcium transport, b sodium to chloride permeability ratio (P Na/P Cl), c solvent drag-induced calcium transport, d paracellular passive calcium transport, and e paracellular permeability to calcium (P Ca) in the duodenum of 2-week swimming and age-matched sedentary rats. Transcellular active calcium flux was measured under mucosal glucose-free conditions, which reduced solvent drag-induced transport. The solvent drag-induced calcium flux was determined in the presence of serosal 0.1 mmol/L trifluoperazine, an inhibitor of PMCA. Paracellular passive calcium flux was determined in the presence of the transepithelial calcium gradient (1.25 mmol serosal calcium; 5, 10, 20, 40, and 80 mmol/L mucosal calcium). The first value of each paracellular graph was calcium flux in the absence of transepithelial calcium gradient (1.25 mmol/L calcium on both sides); therefore, this value represents the transcellular active calcium flux plus solvent drag-induced calcium flux. Δ[Ca] denotes the result from subtraction of serosal calcium (1.25 mmol/L) from mucosal calcium. *P < 0.05, **P < 0.01 compared with its respective sedentary group. Numbers in parentheses are the numbers of animals