A5084438654- Ion Transport and Channel Regulation
- Ion channel regulation and function
- Neuroscience and Neuropharmacology Research
- Pancreatic function and diabetes
- Nitric Oxide and Endothelin Effects
- Photoreceptor and optogenetics research
- Renal function and acid-base balance
- Erythrocyte Function and Pathophysiology
- Neuroscience of respiration and sleep
- Lipid Membrane Structure and Behavior
- Cardiac electrophysiology and arrhythmias
- Electrolyte and hormonal disorders
- Hemoglobin structure and function
- Receptor Mechanisms and Signaling
- Physiological and biochemical adaptations
- Enzyme function and inhibition
- Eicosanoids and Hypertension Pharmacology
- Electrochemical Analysis and Applications
- Amino Acid Enzymes and Metabolism
- Neuroscience and Neural Engineering
- Membrane-based Ion Separation Techniques
- ATP Synthase and ATPases Research
- Drug Transport and Resistance Mechanisms
- Molecular Sensors and Ion Detection
- Diet and metabolism studies
Case Western Reserve University
2016-2025
University School
2016-2025
Yale University
2003-2024
Institute of Molecular Biology and Biophysics
2009-2015
Medizinische Hochschule Hannover
2006-2011
Johannes Kepler University of Linz
2011
Cellular Research (United States)
2007
Brigham and Women's Hospital
1997
Harvard University Press
1996
University of Oxford
1996
The intracellular pH (pHi) of squid giant axons has been measured using glass microelectrodes. Resting pHi in artificial seawater (ASW) (pH 7.6-7.8) at 23 degrees C was 7.32 +/- 0.02 (7.28 if corrected for liquid junction potential). Exposure the axon to 5% CO2 constant external caused a sharp decrease pHi, while subsequent removal gas overshoot its initial value. If exposure prolonged, two additional effects were noted: (a) during exposure, rapid fall followed by slow rise, and (b) after...
We have used pH-, Na-, and Cl-sensitive microelectrodes to study basolateral HCO3- transport in isolated, perfused proximal tubules of the tiger salamander Ambystoma tigrinum. In one series experiments, we lowered pH (pHb) from 7.5 6.8 by reducing [HCO3-]b 10 2 mM at a constant pCO2. This reduction pHb causes large (approximately 0.35), rapid fall pHi as well transient depolarization membrane. Returning normal has opposite effects. Similar reductions luminal (pHl) [HCO3-]l only minor The...
We have developed a technique to measure the fluorescence of pH-sensitive dye (2,7-biscarboxyethyl-5(6)-carboxyfluorescein) in single glomerular mesangial cells culture. The intracellular excitation ratio was calibrated using nigericin-high-K+ approach. In absence CO2-HCO3-, that are acid loaded by an NH+4 prepulse exhibit spontaneous pH (pHi) recovery is blocked either ethylisopropylamiloride (EIPA) or removal external Na+. This pHi most probably reflects activity Na+-H+ exchanger. When...
Trypanosoma cruzi invades most nucleated cells by a mechanism distinct from classical phagocytosis. Although parasites enter at the lysosome-poor peripheral cell margins, lysosomal markers are immediately incorporated into parasitophorous vacuole. No accumulation of polymerized actin was detected around recently internalized parasites, and disruption microfilaments significantly facilitated invasion. Lysosomes were observed to aggregate sites trypanosome attachment fuse with vacuole early...
It is generally accepted that gases such as CO 2 cross cell membranes by dissolving in the membrane lipid. No role for channels or pores gas transport has ever been demonstrated. Here we ask whether expression of water channel aquaporin-1 (AQP1) enhances permeability Xenopus oocytes. We expressed AQP1 oocytes injecting cRNA, and assessed using microelectrodes to monitor changes intracellular pH (pH i ) produced adding 1.5% /10 mM[Formula: see text] (or removing it from) extracellular...
Using pH-sensitive microelectrodes to measure intracellular pH (pHi) in isolated, perfused proximal tubules of the tiger salamander Ambystoma tigrinum, we have found that when cells are acid-loaded by pretreatment with NH+4 a nominally HCO3--free Ringer, pHi spontaneously recovers an exponential time course. This recovery, which is indicative active (i.e., uphill) transport, blocked removal Na+ from both luminal and basolateral bath) solutions. Re-addition either lumen or bath results full...
The water channel aquaporin 1 (AQP1) and certain Rh-family members are permeable to CO 2 NH 3 . Here, we use changes in surface pH (pH S ) assess relative vs. permeability of Xenopus oocytes expressing the AQP or Rh family. Exposed , AQP1 exhibit a greater maximal magnitude change (ΔpH compared with day-matched controls injected H O RNA encoding SGLT1, NKCC2, PepT1. With also have faster time constants for relaxation (τ pHs ). Thus, AQP1, but not other proteins, conduct Oocytes rat AQP4,...
Angiotensin II (AII) is a potent stimulus for HCO3- reabsorption in the rat proximal tubule vivo. To determine ionic mechanism of increased reabsorption, we have examined effect AII on luminal Na(+)-H+ exchange and basolateral Na+/HCO3- cotransport perfused S1 tubules isolated from superficial nephrons rabbit kidney. Transporter activity was assessed by removing Na+ both (i.e., bath) solutions determining rate at which intracellular pH (pHi) after returned to only lumen or bath. pHi measured...
We report here the application of a previously described method to directly determine CO2 permeability (P(CO2)) cell membranes normal human red blood cells (RBCs) vs. those deficient in aquaporin 1 (AQP1), as well AQP1-expressing Xenopus laevis oocytes. This measures exchange (18)O between CO2, HCO3(-), and H2O suspensions. In addition, we measure alkaline surface pH (pH(S)) transients caused by dominant effect entry HCO3(-) into oocytes exposed step increases [CO2]. that 1) AQP1 constitutes...
Active ion-coupled glutamate transport is of critical importance for excitatory synaptic transmission, normal cellular function, and epithelial amino acid metabolism. We previously reported the cloning rabbit intestinal high affinity transporter EAAC1 (Kanai, Y., Hediger, M. A.(1992) Nature 360, 467-471), which [Medline] expressed in numerous tissues including intestine, kidney, liver, heart, brain. Here, we report a detailed stoichiometric kinetic analysis Xenopus laevis oocytes. Uptake...