Two projects are described in this application. Both emphasize the relation of cell structure to epithelial transport. 1. The action of ADH: a scanning and transmission electron microscopie study. We have been able to apply current high-resolution techniques in both scanning and transmission electron microscopy (SEM and TEM) to the problem of the intracellular action of antidiuretic hormone (ADH). We will use both SEM and TEM to determine in detail the structure of the terminal web of the toad bladder epithelial cell, and the specific filamentous attachments of the cytoplasmic tubules to the luminal membrane and surrounding cytoskeleton. These tubules fuse to the membrane in response to ADH, and deliver water-conducting particles to the membrane. We have proposed a """"""""tilting"""""""" mechanism for tubule fusion, and will seek evidence for this mechanism. We will employ tannic acid-fixed sections, resinless sections and sections coated with ultrathin metal films in our SEM and TEM sections. We will identify specific cytoskeletal components by immunocytochemistry at the light and EM level. We will isolate and characterize the water-conducting particles. We will use our techniques in a study of the mammalian kidney, emphasizing glomerular cytoskeletal structure. 2. Autoradiography of diffusible solutes. Refinements in our system of """"""""dry"""""""" autoradiography permit the study of the transport of water-soluble solutes such as urea across epithelia, and the effects of hormones and inhibitory agents on transport. These studies will now be extended to two new problems: the paracellular transport of ions and non-electrolytes across """"""""leaky"""""""" epithelia, and the active transport of iodide by the choroid plexus. Both projects bring new techniques to the problem of epithelial transport. There is increasing interest in fusion and exocytosis in such phenomena as neurotransmission and hormone secretion; the ADH system under investigation in this application provides one of the most clear-cut examples of the relationship of the cytoskeleton to fusion. In the human kidney, glomerular filtration appears to be greatly influenced by the contractile properties of the mesangial cell and other cellular elements surrounding the basement membrane; these may be altered in important ways in renal disease. Our autoradiographic studies show cellular transport in a new way, and add to our understanding of water and electrolyte movement.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK003858-26
Application #
3224428
Study Section
Physiology Study Section (PHY)
Project Start
1976-05-01
Project End
1989-06-30
Budget Start
1987-07-01
Budget End
1988-06-30
Support Year
26
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Type
Schools of Medicine
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461
Hays, R M (1996) Cellular and molecular events in the action of antidiuretic hormone. Kidney Int 49:1700-5
Franki, N; Macaluso, F; Gao, Y et al. (1995) Vesicle fusion proteins in rat inner medullary collecting duct and amphibian bladder. Am J Physiol 268:C792-7
Franki, N; Macaluso, F; Schubert, W et al. (1995) Water channel-carrying vesicles in the rat IMCD contain cellubrevin. Am J Physiol 269:C797-801
Hays, R M; Franki, N; Simon, H et al. (1994) Antidiuretic hormone and exocytosis: lessons from neurosecretion. Am J Physiol 267:C1507-24
Simon, H; Gao, Y; Franki, N et al. (1993) Vasopressin depolymerizes apical F-actin in rat inner medullary collecting duct. Am J Physiol 265:C757-62
Gao, Y; Franki, N; Macaluso, F et al. (1992) Vasopressin decreases immunogold labeling of apical actin in the toad bladder granular cell. Am J Physiol 263:C908-12
Franki, N; Ding, G; Gao, Y et al. (1992) Effect of cytochalasin D on the actin cytoskeleton of the toad bladder epithelial cell. Am J Physiol 263:C995-1000
Holmgren, K; Magnusson, K E; Franki, N et al. (1992) ADH-induced depolymerization of F-actin in the toad bladder granular cell: a confocal microscope study. Am J Physiol 262:C672-7
Hays, R M; Lindberg, U (1991) Actin depolymerization in the cyclic AMP-stimulated toad bladder epithelial cell, determined by the DNAse method. FEBS Lett 280:397-9
Singhal, P C; DeCandido, S; Satriano, J A et al. (1989) Atrial natriuretic peptide and nitroprusside cause relaxation of cultured rat mesangial cells. Am J Physiol 257:C86-93