Molecular and Functional Study of Ion Transporters in Membranes

• Grant number: 95/04628-4
• Support Opportunities: Research Projects - Thematic Grants
• Start date: May 01, 1996
• End date: May 31, 2000
• Field of knowledge: Biological Sciences - Biophysics - Cellular Biophysics
• Principal Investigator: Gerhard Malnic
• Grantee: Gerhard Malnic
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant(s): 99/08354-7 - Actin depolymerizing factor t-complex polypeptide 1, a variant of [gamma-glutamylcysteine synthetase and seleprotein p are among up-regulated proteins in renal tissue after short periods of ischemia., AR.EXT; 98/11373-0 - V1 receptors in luminal action of vasopressin (AVP) on distal K+ secretion, AR.EXT; 98/11529-0 - Chronic effect of parathyroid hormone on na/h exchanger type 3 isoform protein and mrna in renal proximal tubules., AR.EXT; + associated grants 98/07983-8 - David C. Spray | Albert Einstein College of Medicine - Estados Unidos, AV.EXT; 97/12633-3 - Gerhard Giebisch | Yale University School of Medicine - Estados Unidos, AV.EXT; 97/04487-7 - David Conover Spray | Albert Einstein College of Medicine - Estados Unidos, AV.EXT; 97/00588-3 - "effect of luminal angiotensin ii and anp on early and late cortical distal tubule hco3 reabsorption"., PUB.ART - associated grants

Abstract

The group of Renal Biophysics of the Department of Physiology and Biophysics, ICB-USP, has in the past studied the mechanisms of ion transport in renal tubules of the mammalian kidney. Ion-sensitive microelectrodes for the determination of pH and potassium activity were develloped, including antimony and ion exchange resin based microelectrodes. These electrodes were used to study the mechanism of bicarbonate reabsorption and of potassium secretion in proximal and distal tubules of the renal cortex, as well as their regulation by hormonal factors. These studies benefited from the devellopment of a kinetic technique of analysis of stationary microperfusion experiments. More recently, the laboratory directed its interest toward more modern methods at the cellular and molecular level, including: 1- Molecular biology of membrane transporters, particularly of the Na/H exchanger and its isoforms, including the modulation of their expression during pathophysiological alterations of exchanger activity; 2- Determination of cellular ion activity by fluorescence microscopy, particularly of pH and calcium, in order to study mechanisms of cell homeostasis of these ions and their regulation; 3- Analysis of ion channels by the patch-clamp technique, including the properties of K and Ca channels in renal and other cells as well as the effect of spider toxins on these channels; 4- Functional characterization of Na-K dependent and of Na-dependent ATPases in insect renal tubules (Rhodnius, a transmitter of Chagas disease); and 5- Study of the mechanisms of volume regulation of insect and mammalian renal cells in hypotonic and hypertonic media. (AU)