Table 1.

Tubular diameters and transport parameters

Tubule or vessel	Lp (cm mmHg/s)	PNa+ (10−5 cm/s)	Purea (10−5 cm/s)	$V_{\max ,{\mathrm{Na}}^{+}}^{\mathrm{abs}}$ (nmole/(cm2·s))	$V_{\max ,\mathrm{urea}}^{\sec }$ (nmole/(cm2·s))
PST	3.36×10−7	10	1.5	2.1	10
SDL	3.06×10−7| 0	1.5 | 1.1	7.4 | 200	0.43 | 0	0
OM LDL	2.16×10−7	63	0.5	0.43	0
IM LDL	2.07×10−7| 0	0	13 | 180	0	0
IM LDLS	0	0	200	0	0
SAL	0	1.1	1.4 | 0.9	10.5 | 25.9	0
OM LAL	0	1.1	1.4 | 0.6	10.5 | 25.9	0
IM LAL	0	80	190	0	0
OMCD	4.23×10−8	1	0.3	0	0
IMCD	4.23×10−8	1	0.5 to 110	8.5→4	0

PST, proximal straight tubule; SDL/LDL, short/long descending limb; SAL/LAL, short/long ascending limb; CD, collecting duct; LDL_S, LDL that turns within the first mm of the IM. Arrow (→) indicates that parameter is assumed to vary linearly as x increases; vertical line (|) indicates that parameter is assumed to change abruptly. Axial variations in IMCD $V_{\max ,{\mathrm{Na}}^{+}}^{\mathrm{abs}}$ are given in Ref. (24).