Table 1.

3-C model parameters identified by fitting the model to the plasma profile of Δ⁴¹K/³⁹K in rats maintained on a control (1% K⁺) or K⁺-deficient (0% K⁺) diet.

	Control	K+-Deficient Diet	% Change
k01	0.0043 ± 0.0024	0.0003 ± 0.0003 ***	↓95%
k21	0.317 ± 0.166	0.298 ± 0.094	↓6%
k12	0.041 ± 0.014	0.026 ± 0.005 *	↓37%
k31	0.220 ± 0.100	0.199 ± 0.075	↓9%
k13	0.0058 ± 0.0020	0.0038 ± 0.0007 *	↓34%
KECF	0.49 ± 0.19	0.31 ± 0.14 *	↓37%
KICF2 (fast)	3.70 ± 2.22	3.33 ± 0.98	↓10%
KICF3 (slow)	16.9 ± 1.6	14.4 ± 1.5 **	↓15%

k₀₁ was estimated from renal K⁺ excretion measured from urine collected from the bottom of the cage (see the Methods section); five parameters (K_ECF, K_ICF2, K_ICF3, k₂₁, and k₃₁) were identified by fitting the model to the data; and k₁₂ and k₁₃ were calculated as K_ECF × (k₂₁/K_ICF2) and K_ECF × (k₃₁/K_ICF3), respectively. Units are min⁻¹ for k₀₁, k₂₁, k₁₂, k₃₁, and k₁₃ and mEq/300g BW for K_ECF, K_ICF2, and K_ICF3. Data are mean ± SD (n = 6 for control and 7 for K⁺ deficient diet). *, p < 0.05; **, p < 0.01; ***, p < 0.001 vs. control (two-tailed t-test for the rate constants and one-tailed t-test for K_ECF, K_ICF2, and K_ICF3; p values were not corrected for multiple comparisons to increase the power of detecting changes, at the risk of false positives). ↓ represents a decrease.