Ano. Dodoo et al., Systematic investigations of the influence of molecular structure on the transport of peptides across cultured alveolar cell monolayers, PHARM RES, 17(1), 2000, pp. 7-14
Purpose. To determine how the structures of peptides influence their alveol
ar permeability.
Methods. The studies were performed using 14 synthetic 'model' peptides, la
belled with a novel, non-intrusive amino acid fluorophore, and their transp
ort studied using rat alveolar cell monolayers cultured on permeable suppor
ts.
Results. The passage of the peptides across the epithelial cell monolayers
is shown to be primarily paracellular, with an inverse dependence on molecu
lar size, and an enhanced flux observed for cationic peptides. The apparent
permeability coefficients (P-app) for the peptides (together with those fo
r other organic solutes, taken from the literature) are shown to be well-mo
delled assuming two populations of 'pores' in the monolayers, modelled as c
ylindrical channels of radii 15 Angstrom and 22 nm. The former pores are sh
own to be numerically equatable with the monolayer tri-junctional complexes
, and the latter are taken as monolayer defects.
Conclusions. The various monolayer P-app values correlate well with the res
ults from in vivo transport experiments, and the conclusion is drawn that t
he pulmonary delivery of peptide drugs is perfectly exploitable.