Physical properties of isolated perfused renal tubules and tubular basement membranes
AUTOR(ES)
Welling, Larry W.
RESUMO
To study the physical properties of renal tubular basement membranes directly, the epithelial layer of single isolated perfused rabbit proximal convoluted, proximal straight, and cortical collecting tubules was removed with sodium desoxycholate. Tubular segments were perfused using micropipets. The distal end of each segment was occluded in order to simplify the measurement of transmembrane water flow. The relation between outer tubular diameter and applied transmural pressure was identical in intact tubules and their respective isolated tubular basement membranes indicating that the basement membrane determines tubular distensibility. Young's modulus for basement membranes from all tubular segments corresponded to that of tendon collagen. Membrane hydraulic conductivity was measured in two ways: (a) from the rate of transmural flow in response to an applied difference in hydrostatic pressure and, (b) from the rate of transmural flow in response to a difference in colloid osmotic pressure. The hydraulic conductivity of tubular basement membranes was 300-800 times greater than that of the intact epithelial layer. Basement membrane hydraulic conductance was similar to that of peritubular and glomerular capillaries in vivo. The hydrostatic conductance of tubular basement membranes exceeded the osmotic conductance by 3-10-fold owing largely to the fact that the membranes were moderately permeable to the osmotic solute (albumin). In view of these findings we suggest that oncotic and hydrostatic pressure may play an important role in the movement of tubular absorbate from the epithelial compartment into the renal interstitium.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=292235Documentos Relacionados
- Cell membranes and paracellular resistances in isolated renal proximal tubules from rabbit and Ambystoma.
- Albumin absorption and catabolism by isolated perfused proximal convoluted tubules of the rabbit.
- Effect of Peritubular Protein Concentration on Reabsorption of Sodium and Water in Isolated Perfused Proximal Tubules
- Carbon dioxide causes exocytosis of vesicles containing H+ pumps in isolated perfused proximal and collecting tubules.
- Ammonia production by isolated mouse proximal tubules perfused in vitro. Effect of metabolic acidosis.