Solvent drag

JR Pappenheimer, KZ Reiss. Contribution of solvent drag through intracellular junctions to absorption of nutrients by the small intestine of the rat. J Membrane Biol 100 123-136, 1987. 

A Karino, M Hayashi, T Horie, S Awaza, H Minami, M Hanano. Solvent drag effect in intestinal drug absorption. J Pharmacobiol Dynam 5 410-417, 670-677, 1982. 

Fagerholm, U., Nilsson, D., Knutson, L., Lennernas, H., Jejunal permeability in humans in vivo and rats in situ investigation of molecular size selectivity and solvent drag, Acta Physiol. Scand. 1999, 165, 315-324. 

With an increase in pH, there is an increased absorption of mercuric chloride [6, 7], whereas accumulation of mercury in the intestinal tissue decreases. Mercury absorption is inversely proportional to its accumulation in the tissue. An increase in water absorption due to hypotonicity or an increase in concentration of sodium ions or urea increases the mercury absorption and accumulation in the epithelial cell, without change in the intracellular distribution pattern [8], Thus, the absorption of mercury is thought to accompany the solvent drag and to be influenced by pH change in the intestinal lumen. 

Osmolarity of perfusate solution The buffer osmolarity should be standardised to facilitate estimation of Peff values. Generally adjusted to physiological conditions of 290 mOsm/kg. (70 mM phosphate buffer) with 5.4 mM potassium chloride, 48 mM sodium chloride, 35 mM mannitol, and 10 mM D-glucose. Lane et al. [131] demonstrated the effect of hypersomolar perfusion on Tapp of ibuprofen in the in situ rat gut technique. Hypersomolar solutions tended to decrease Peff values, attributable to a reversed solvent drag effect. 

Another means of transport across the intestine is via the paracellular route, that is between the adjacent enterocytes. Water can enter the intestinal space throngh this ronte and take with it small molecnles inclnding glncose, amino acids and small peptides. This is known as solvent drag (Figure 4.7). Unfortunately, the qnantitative importance of this route is not known. 

A high concentration of Ca in the intestinal lumen relative to the ECF tends to drive Ca absorption via the paracellular route. Water naturally seeps through the "microspaces (Wasserman, 2004), or cellular jimctions between adjacent enterocytes, during absorption thus creating a paracellular pathway between which 8-30% of the total Ca absorbed (McCormick, 2002) is entrained as a solute. The transfer of Ca by a solvent drag-induced mechanism is via a passive diffusion process in response to increases in the osmolarity of the lumenal contents. This pathway is not site specific and the opportunity for Ca absorption via this route occurs throughout the entire length of the small intestine (Weaver and Liebman, 2002). 

Non-ionic polymer gel, swollen with dielectric solvent, can be extremely deformed as is the case for non-ionic polymer plasticised with non-ionic plasticiser. Instead of the charge-injected solvent drag as a mechanism of the gel actuation, the principle is based on local asymmetrical charge distribution at the surface of the gel18. The mechanism can also be applied to non-ionic elastomers in which the motion of the polymer chain is relatively free. In spite of their many difficulties for practical actuators, polyelectrolyte gels and related materials are the most interesting electroactive polymer materials. 

NaCIO is an acknowledged novel absorption enhancer for ampicillin sodium [99], glycyr-rhizin [100,101], gentamicin [102], phenoxymethyl penicillin [103], cefoxitin sodium [104,105], and acyclovir [106], Takahashi et al. [107] reported that the enhanced membrane permeability of phenolsulfonphthalein depends on the disappearance kinetics of CIO from the loop and its calcium ion sequestration capacity. The enhancing mechanisms of NaCIO are proposed to be involved in (1) Ca2+ sequestration, (2) increase in pore size and solvent drag, (3) interaction with membrane proteins and lipids, and (4) increase in the intracellular calcium level [104,105,108-111],... 

Karino, A., et al. 1982. Solvent drag effect in drug intestinal absorption. I. Studies on drug and D20 absorption clearances. J Pharmacohiodyn 5 410. 

Nicklin P, Irwin B, Hassan I et al. (1992) Permeable support type influences the transport of compounds across CACO-2 cells. Int J Pharm 93 197-209 Pappenheimer JR, Reiss KZ (1987) Contribution of solvent drag through intercellular junctions to absorption of nutrients by the small intestine of the rat. J Membr Biol 100 123-136 Peters WHM, Reolofs HMJ (1992) Biochemical characterization of resistance to mitoxantrone and adriamycin in CACO-2 human colon adenocarcinoma cells a possible role for glutathione-S-transferase. Cancer Res 52 1886-1890... 

H. Ochsenfahrt and D. Winne. Contribution of solvent drag to the intestinal absorption of the basic dmgs amidopyrine and antipyrine from the jejunum of the rat. Arch. Pharmacol. (NS), 281, 195-6(1974)... 

The four pathophysiologic mechanisms of diarrhea have been linked to the four broad diarrheal groups, which are secretory, osmotic, exudative, and altered intestinal transit. The three mechanisms by which absorption occurs from the intestines are active transport, diffusion, and solvent drag. 

Absorption from the intestines back into the blood occurs by three mechanisms active transport, diffusion, and solvent drag. Active transport and diffusion are the mechanisms of sodium transport. Because of the high luminal sodium concentration (142 mEq/L), sodium diffuses from the sodium-rich gut into epithelial cells, where it is actively pumped into the blood and exchanged with chloride to maintain an isoelectric condition across the epithelial membrane. 

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