Table 5.

Predicted impact of parathyroid hormone on PO₄ transport

			JPO4, pmol·min−1·mm−1 per nephron
	Filtered Load, pmol/min per nephron	%Reabsorption	Net	Transcellular	Paracellular
Base case	78.0	79.2	5.62	7.14	−1.52
75% inhibition of Na+-PO4 transporters	78.0	54.7	3.88	2.69	+1.19
90% inhibition of Na+-PO4 cotransporters	78.0	46.2	3.27	1.26	+2.01
NHE3 inhibition*	78.0	94.8	6.73	9.92	−3.19
NHE3 inhibition* and 75% inhibition of Na+-PO4 cotransporters	78.0	55.5	3.93	4.16	−0.23
NHE3 inhibition* and 90% inhibition of Na+-PO4 cotransporters	78.0	38.6	2.73	1.97	+0.76
20% reduction in SNGFR	62.4	67.1	3.81	4.47	−0.66
20% reduction in SNGFR, NHE3 inhibition* and 75% inhibition of Na+-PO4 cotransporters	62.4	47.7	2.70	2.59	+0.11
20% reduction in SNGFR, NHE3 inhibition* and 90% inhibition of Na+-PO4 cotransporters	62.4	35.8	2.03	1.22	+0.81

J_PO4, flux of PO₄ (${\text{HPO}}_4^{2-}$+ ${\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}^{-}$); NHE3, Na⁺/H⁺ exchanger type 3; SNGFR, single-nephron glomerular filtration rate. Fractional inhibition of Na⁺-PO₄ cotransporters NaPi-IIa, NaPi-IIc, and PiT-2 is taken to be the same.

^*Parathyroid hormone is assumed to reduce basal expression of NHE3 and Na⁺-K⁺-ATPase by 75% and 25%, respectively.