Lang S, Rothen-Rutishauser B, Perriard J C, Schmidt M C, Merkle H P
Department of Pharmacy, Swiss Federal Institute of Technology Zurich (ETH), Switzerland.
Peptides. 1998;19(3):599-607. doi: 10.1016/s0196-9781(97)00470-1.
In vitro permeation of human calcitonin (hCT), salmon calcitonin (sCT), and the somatostatin analog octreotide (SMS) through excised bovine nasal mucosa was studied applying donor/receiver experiments and confocal laser scanning microscopy. Permeabilities of gonadorelin, buserelin, Hoe013, and of thymopoietin fragments TP5 and TP4 were also included. Apparent permeability coefficients (Peff) ranged between 4 x 10(-5) (SMS) and 1.7 x 10(-5) cm s(-1) (TP4). Such Peff are typical for leaky-type airway epithelia. The order of permeabilities was: SMS >> hCT, sCT > buserelin, Hoe013 >> TP5 > TP4, LHRH. The relatively high permeability of hCT and sCT contrasted to their high molecular weight. At 37 degrees C, the permeability of hCT from mucosal to serosal (m-to-s) was found two-fold higher (p < 0.05) than from serosal to mucosal (s-to-m). Controls using 3H-mannitol showed equal permeabilities in both directions. At 4 degrees C, permeation of hCT was reduced but equal in both directions (m-to-s and s-to-m). As evaluated by confocal laser scanning microscopy, uptake studies with FITC-18-hCT revealed intracellular fluorescence in the epithelial cells, at 10 min/10 microM exposure in the form of fluorescent vesicles. By combination of these findings, an endocytotic pathway is suggested to contribute to the transport of hCT through nasal epithelium.
