Regional permeability of coenzyme Q10 in isolated rat gastrointestinal tracts

The objective of the study was to identify the region with the maximum permeability for low bioavailable coenzyme Q10 (CoQ) in the gastrointestinal tract. To evaluate the regional differences in permeability, male Sprague-Dawley rats, 250-300 g, were anesthetized and the gastrointestinal segments were isolated. Stomach, duodenum, jejunum, ileum and colon tissues were mounted on a Navicyte side-by-side diffusion apparatus. Radiolabeled CoQ (1 microM in DMEM, pH 7.4, 37 degrees C was added to the donor side and the samples withdrawn from the receiver compartment at predetermined time intervals were analyzed using a scintillation counter. Membrane integrity was monitored by 14C-mannitol permeability. The apical to basal permeability coefficients (Papp x 10(-6), cm/s) were 0.32 +/- 0.13, 3.14 +/- 0.89, 1.36 +/- 1.4, 0.83 +/- 0.40, and 1.59 +/- 0.13, for CoQ through rat stomach, duodenum, jejunum, ileum, and colon tissues respectively. The basolateral to apical permeability coefficients (Papp x 10(-6), cm/s) were 1.6 +/- 0.2, 2.2 +/- 1.2, 0.88 +/- 0.12, 1.6 +/- 0.42, and 1.9 +/- 0.41 respectively. Therefore the region of maximum CoQ permeability is duodenum followed by colon and ileum. Jejunum and stomach regions also have fairly high permeability. Therefore CoQ formulations should be made with an aim to target the duodenum to get maximum dosage effect.