Table 2.

Transport parameters of macula densa cells

Transporter	Value	Unit	Reference
Na+/H+ exchanger density (apical)	6	10−9 mmol/cm2	(48)
Na+-K+-ATPase density	1,040	10−9 mmol/s/cm2	Estimated
K+ apical permeability	40	10−5 cm/s	(19)
K+ basolateral permeability	0.2	10−5 cm/s	Estimated
Cl− basolateral permeability	5.0	10−5 cm/s	Estimated
HCO3− basolateral permeability	0.5	10−5 cm/s	Estimated
Pf, apical membrane	133	10−4 cm/s	(12)
Pf, tight junction	700	10−4 cm/s	(48)
Pf, basolateral membrane	1,687	10−4 cm/s	(12)

P_f, osmotic permeability. Other transport parameters are identical to those of the TAL and are listed in Table 1 in Ref 48.