Glycerol permeability

Kuang K, Yiming M, Wen Q, Li Y, Ma L, Iserovich P, Verkman AS, Fischbarg 1 (2004) Fluid transport across cultured layers of corneal endothelium from aquaporin-1 null mice. Eixp Eye Res 78 791—798 Kuriyama H, Kawamoto S, Ishida N, Ohno 1, Mita S, Matsuzawa Y, Matsubara K, Okubo K (1997) Molecular cloning and expression of a novel human aquaporin from adipose tissue with glycerol permeability. Biochem Biophys Res Commun 241 53—58... 

The mode of action of glycerol both on SC hydration and epidermal barrier function seems to be related to the aquaporin-3 (AQP3) channel. The basal layer of epidermal keratinocytes contains AQP3, a small membrane protein that functions as a facilitated transporter of water and glycerol.11 Glycerol is transported very slowly into the epidermis and thus its transport rate is sensitive to the intrinsic glycerol permeability of the basal keratinocyte layer. 

H. Kuriyama, S. Kawamoto, and N. Ishida, et ah. Molecular cloning and expression of a novel human aquaporin from adipose tissue with glycerol permeability, Biochem. Biophys. Res. Commun., 1997, 241, 53-58. 

Beitz E, Pavlovic-Djuranovic S, Yasui M et al. Molecular dissection of water and glycerol permeability of the aquaglyceroporin from Plasmodium felciparum by mutational analysis. Proc Natl Acad Sci USA 2004 101(5) 1153-1158. 

Brown FF,Sussman I, Avron M and Degani H (1982) NMR studies of glycerol permeability in lipid vesicles, erythrocytes and the alga Dunaliella, Biochim. Biophys. Acta, 690, 165-173. 

Helliwell RM, Large WA 1997 Alphal-adrenoceptor activation of a non-selective cation current in rabbit portal vein by 1,2-diacyl-sn-glycerol. J Physiol 499 417-428 Hofmann F, Lacinova L, Klugbauer N 1999 Voltage-dependent calcium channels from structure to function. Rev Physiol Biochem Pharmacol 139 33—87 Hofmann T, Schaefer M, Schultz G, Gundermann T 2000 Transient receptor potential channels as molecular substrates of receptor-mediated cation entry. J Mol Med 78 14—25 Inoue R, Okada T, Onoue H et al 2001 The transient receptor potential protein homologue TRP6 is the essential component of vascular aj-adrenoceptor-activated Ca2+-permeable cation channel. Circ Res 88 325—332... 

L. lactis is the first Gram-positive bacterium in which a MIP channel has been functionally characterised. The lactococcal MIP protein is shown to be permeable to glycerol, like E. coli GlpF, and to water, like E. coli AQPZ. That was the first description of a microbial MIP that has a mixed function. This result provided important insights for reconstructing the evolutionary history of the MIP family and elucidating the molecular pathway of water and other solutes in these channels [86]. 

Thus, the apparent membrane permeability characteristics of hydrophilic compounds listed in Table 3.4 indicate that colonic epithelium is different from small intestinal epithelium in selectivity, or size or density distribution of the paracellular pathway. This is further complicated because of the possible involvement of unidentified carriers or channels for some compounds, as suggested for glycerol and D-xylose. However, the colon-to-SI ratios of the apparent membrane permeability are generally comparable with (or lower than) those calculated considering the morphological surface area, suggesting that such factors are not in favor for colonic absorption in most cases. Matching... 

Note Data represent the mean S.E. (n = 3). MW, molecular weight P0/w, octanol-to-water partition coefficient CLapp, apparent membrane permeability clearance SI, midgut area of the small intestine NA, not available or applicable. Absorption was evaluated in our laboratory using the closed loop of the rat intestine in situ (urethane anesthesia, 1.125 g/4.5 ml/kg, i.p.) in 60 min for riboflavin and L-camitine and 30 min for the others. For those that are transported by carriers in part (riboflavin and glycerol in both colon and SI, and L-carnitine, 5-fluorouracil, and cephradine in SI), absorption was evaluated at higher concentrations where the contribution of carrier-mediated transport is negligible. Values of P0/w were obtained from a report by Leo et al. [30] except for that of D-xylose, which was determined in our laboratory. a Data by single-pass perfusion experiments. b Unpublished data from our laboratory. 

Cells of E. coli can adapt to at least 100-fold changes in osmolarity. Because of the porosity of the bacterial outer membrane the osmolarity of the periplasmic space is normally the same as that of the external medium. However, the inner membrane is freely permeable only to water and a few solutes such as glycerol.b The bacterial cells avoid loss of water when the external osmolarity is high by accumulating K+ together with anions such as... 

Ishibashi K, Kuwahara M, Gu Y, Tanaka Y, Marumo F, Sasaki S. 1998. Cloning and functional expression of a new aquaporin (AQP 9) abundantly expressed in the peripheral leukocytes permeable to water and urea, but not to glycerol. Biochem Biophys Res Com 244 268-274. 

Schreier et al. [85] examined the effects of liposome encapsulation on the pharmacokinetics in sheep of amikacin, a water-soluble aminoglycoside. The dmg was formulated in 200 nm liposomes and administered by means of intratracheal instillation. The liposome formulations were soy PC/phosphatidyl glycerol (PG) (7 3 molar ratio) and soy PC/PG/CH (4 3 3). They found that both liposome formulations reduced plasma Cmax and prolonged the plasma half-life of the amikacin compared with the dmg administered as a solution, once again indicating that liposomes were controlling dmg delivery in the lungs. The inclusion of cholesterol in liposomes more than tripled the plasma half-life for the dmg compared with the liposomes without cholesterol. Cholesterol reduces the fluidity and permeability of liposomes in their liquid crystalline phase. 

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