Retrieval of Water Channels by Endocytosis in Renal Epithelia.
Abstract
Pretreatment and removal of vasopressin (ADH) in toad urinary bladder renal model tissues induces endocytosis at 25 deg C. This study was carried out to determine if apical membrane remodeling, as well as transepithelial water flow, can be affected by lowering the temperature to 15 deg C. Control toad urinary bladders in the presence of an osmotic gradient at either 25 or 15 deg C when visualized by scanning electron microscopy (SEM) show a typical apical membrane surface with no apparent surface differences. ADH-treated tissues following 15 min stimulation at 25 or 15 deg C revealed a propagation of apical microvilli on their surface membranes. After 15 min following removal of ADH, bladder tissues at 25 or 15 deg C showed surface invaginations involving over 44% and 80% of granular cells, respectively. The rate of water flow in tissues at 15 deg C remained elevated compared to tissues held at 25 deg C. This was consistent with the observation that ADH-stimulated tissues following washout at 15 deg C still had marked apical membrane surface involvement. However, at 30 and 60 min post washout, ADH-stimulated tissues at 15 deg C recovered considerably, with a reduction in the number of shallow apical membrane invaginations involving fewer than 33% and 20% of granular cells respectively. This may indicate that the membrane undergoes continuous remodeling even in cold temperature conditions but at a different half-time. Control bladder tissues subjected to transmission electron microscopy (TEM) reveal a dense cytoplsmic profile with scattered distribution of secretory granules, rough ER cisternae, mitochondria and little or no vacuolation. The contrast, ADH-stimulated bladder tissues displayed a vacuolated cytoplasm, expanded rough ER cisternae and ruffled basolateral membranes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1998
- Accession Number
- ADA352485
Entities
People
- Abdul J. Mia
- Thomas Yorio