Transepithelial Transport Characteristics of the Antihypertensive Peptide, Lys-Val-Leu-Pro-Val-Pro, in Human Intestinal Caco-2 Cell Monolayers

An antihypertensive peptide, Lys-Val-Leu-Pro-Val-Pro (KVLPVP), can reduce blood pressure in hypertensive rats after being orally administered. In this study, the transepithelial transport of intact KVLPVP was examined by Caco-2 monolayers. The results were as follows: (i) The flux was not saturable for apical (AP) to basolateral (BL) or BL-AP transport when the concentration of KVLPVP was 1-8 mm. (ii) Sodium deoxycholate loosened the tight junction in the Caco-2 cells and significantly improved the transport process. (iii) Phenylarsine oxide, a transcytotic process inhibitor, had little effect on the transport process. (iv) The influx and eflux of KVLPVP remained unchanged in the presence of the ATP inhibitor sodium azide. (v) This transport was not inhibited by the peptide transporter substrates Gly-Pro or arphanine A. All these data indicate that paracellular transport diffusion was the major flux mechanism for the intact KVLPVP.