Table 3

Permeability of homologous PEG markers relative to mannitol after the addition of CapMul

MarkerKCapMul3-aPCapMul3-b (cm/hr)PPEG/Pman3-cD0× 106d (cm2/sec)DPEG/Dman3-e
[14C]-mannitol0.119  (0.994)0.1449.5
[3H]-PEG 4000.121  (0.994)0.1010.706.00.63
[3H]-PEG 9000.063  (0.997)0.0580.404.20.44
[3H]-PEG 40000.038  (0.998)0.0350.242.10.22
  • 3-a Radioactivity count in CapMul/radioactivity count in an equal volume of Ringer’s buffer, pH 7.4, at 37°C. Results are an average of three determinations ± 6% standard errors. The numbers in parentheses are the percent of the respective radiolabeled marker molecules in the aqueous phase in the presence of CapMul, based on 0.5 ml CapMul in 10 ml of Ringer’s buffer in the donor chamber.

  • 3-b Permeability 55 min after the addition of CapMul (130 min into the experimental protocol). For standard errors and number of tissues, see figure 4B.

  • 3-c Permeability of PEG/permeability of mannitol, after 55 min of the addition of CapMul.

  • 3-d Free solution diffusion coefficient at 37°C, based on D1η1/T1 = D2η2/T2 (Gosting and Morriss, 1988). The free diffusion coefficient of mannitol at 25°C is 7.1 × 106 (Steward, 1982), and those of PEGs are calculated on the basis of D0 = 7 × 10−5 × Mw −0.46 (Johansson et al.,1991 a, b). The viscosities are those of water at T1 = 298 K, η1 = 0.8904 centipoise and T2 = 310 K, η2 = 0.6915 centipoise (Handbook of Chemistry and Physics, 1988).

  • 3-e Free diffusion coefficient of PEG at 37°C/free diffusion coefficient of mannitol at 37°C.