Permeability properties of the intact mammalian bladder epithelium

Abstract

Because the mammalian bladder must store urine of composition which differs markedly from that of plasma for prolonged periods, the bladder permeability barrier must maintain extremely low permeabilities to substances which normally cross membranes relatively rapidly, such as water, protons, and small nonelectrolytes like urea and ammonia. In the present studies, permeabilities of the apical membrane of dissected rabbit bladder epithelium to water, urea, ammonia, and protons were measured in Ussing chambers and averaged (in cm/s) for water, 5.15 +/- 0.43 x 10(-5); for urea, 4.51 +/- 0.67 x 10(-6); for ammonia, 5.14 +/- 0.62 x 10(-4); and for protons, 2.98 +/- 1.87 x 10(-3), respectively. These permeability values are exceptionally low and are expected to result in minimal to no leakage of these normally permeable substances across the epithelium. Water permeabilities in intact whole rabbit bladders were indistinguishable from those obtained in the dissected epithelial preparation. Moreover, addition of nystatin to the apical solution of dissected epithelia rapidly increased water permeability in conjunction with loss of epithelial resistance. These results confirm that the apical membrane of the bladder epithelial cells represents the bladder permeability barrier. In addition, they establish a model system that will permit examination of how membrane structure reduces permeability and how epithelial injury compromises barrier function.

Amniotic Membrane Scaffolds Enable the Development of Tissue-Engineered Urothelium with Molecular and Ultrastructural Properties Comparable to that of Native Urothelium

“…The exceptionally high transepithelial resistance of urothelium results from a high apical plasma membrane transcellular resistance combined with paracellular resistance of tight junctions. 32,33 In the present study, we found that the superficial UCs on sAM were the largest and displayed molecular (uroplakins, occludin) and ultrastructural properties (urothelial plaques, microridges, well-developed tight junctions, and membrane overlaps) of superficial UCs in highly differentiated urothelia. Furthermore, we found that the size of UCs correlated with their differentiation stage, that is, small UCs were less differentiated than larger UCs, which showed properties of highly differentiated UCs.…”

Proteomic Investigation on Chronic Bladder Irritation in the Rat

“…Many of the structural and functional changes associated with human bladder pathology such as neurogenic inflammation and increased mast cell count can be reproduced in a model of HCl-induced chronic irritation 12,13 . Damaged bladder epithelial layer in IC patients leads to bladder irritation from toxins which causes pain and decreased bladder capacity 14,15 . Similarly, the HCl treatment strips off the upper layers of urothelium and weakens the connections between urothelium and stroma 16 .…”

Beyond a Simple Anesthetic Effect: Lidocaine in the Diagnosis and Treatment of Interstitial Cystitis/bladder Pain Syndrome

“…This impermeability is attributed to tight junctions between the apical membrane cells and is most effective at preventing absorption of ionized molecules, as found in the urine. 46 Mishina et al 47 showed that absorption of a weak base molecule was profoundly affected by pH of the bladder content and was optimal at pH >6. Because the route of entry is considered to be directly transmembranal, rather than between cells, lipid solubility (partition coefficient) and molecular size were also shown to be important determinants for the absorption of substances through the bladder epithelium.…”