AGRIMETER FOR MEASUREMENT OF ATMOSPHERIC ELECTRICAL POTENTIAL GRADIENT

1961 ◽  
Vol 18 (6) ◽  
pp. 812-815 ◽  
Author(s):  
B. Vonnegut ◽  
C. B. Moore ◽  
C. K. Harris
Keyword(s):  
Electrical Potential ◽  
Potential Gradient ◽  
Electrical Potential Gradient

A method of determining electrical potential gradient across mitochondrial membrane in perfused rat hearts

1993 ◽  
Vol 265 (2) ◽  
pp. H445-H452 ◽  
Author(s):  
B. Wan ◽  
C. Doumen ◽  
J. Duszynski ◽  
G. Salama ◽  
K. F. LaNoue
Keyword(s):  
Mitochondrial Membrane ◽  
Electrical Potential ◽  
Potential Gradient ◽  
Order Rate Constant ◽  
Isolated Rat Heart ◽  
First Order ◽  
Order Rate ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Electrical Potential Gradient

The electrical potential gradient across the mitochondrial membrane (delta psi m) in perfused rat hearts was estimated by calculating the equilibrium distribution of the lipophilic cation tetraphenylphosphonium (TPP+), using measured kinetic constants of uptake and release of TPP+. First-order rate constants of TPP+ uptake were measured during 30-min perfusions of intact rat hearts with tracer amounts (5.0 nM) of tritium-labeled TPP+ ([3H]TPP+) in the perfusate. This was followed by a 30-min washout, during which the first-order rate constant of efflux was estimated. Values of [3H]TPP+ outside the heart and total [3H]TPP+ inside the heart at equilibrium were calculated. From this information and separately estimated time-averaged plasma membrane potentials (delta psi c) it was possible to calculate free cytosolic [3H]TPP+ at equilibrium. It was also possible to calculate free intramitochondrial [3H]TPP+ at equilibrium as the difference between total tissue [3H]TPP+ minus free cytosolic TPP+ and the sum of all the bound [3H]TPP+. Bound [3H]TPP+ was determined from [3H]TPP+ binding constants measured in separate experiments, using both isolated mitochondria and isolated cardiac myocytes under conditions where both delta psi m and delta psi c were zero. Delta psi m was calculated from the intramitochondrial and cytosolic free TPP+ concentrations using the Nernst equation. Values of delta psi m were 144.9 +/- 2.0 mV in hearts perfused with 5 mM pyruvate and 118.2 +/- 1.4 mV in hearts perfused with 11 mM glucose, in good agreement with delta psi m obtained from isolated rat heart mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of transmembrane electrical potential gradient in rat hepatocytes in situ

1987 ◽  
Vol 252 (1) ◽  
pp. G56-G64 ◽  
Author(s):  
J. G. Fitz ◽  
B. F. Scharschmidt
Keyword(s):  
Electrical Potential ◽  
Potential Gradient ◽  
Rat Hepatocytes ◽  
Solute Uptake ◽  
Tightly Coupled ◽  
Transmembrane Electrical Potential ◽  
Cell Variation ◽  
Over Time ◽  
Electrical Potential Gradient

The transmembrane electrical potential gradient (Em) has been measured in hepatocytes from intact anesthetized rats using conventional intracellular microelectrodes under a variety of conditions. Em measurements in control animals were normally distributed around a mean of -35.5 +/- 4.6 mV (SD) with a coefficient of variation (CV) of 13.1% and a range of -26 to -54 mV. In individual livers, however, measurements of Em at a given point in time exhibited little cell-to-cell variation (cv of 4.5%). The Em was noted to fluctuate spontaneously over time and to change consistently in response to a variety of physiological stimuli including fasting (depolarization to -28.5 +/- 3.8 mV) and infusion of glucagon in physiological amounts (hyperpolarization to -45.0 +/- 1.8 mV). Hepatocyte Em abruptly depolarized (2-5 mV) after an intravenous bolus of taurocholate (3 mumol) or alanine (45 mumol), suggesting that both solutes exhibit electrogenic uptake. The Em returned to or below preinfusion values within 5 min. Continued infusion of alanine (10.8 mumol/min), but not taurocholate (810 nmol/min), caused a sustained and unexpected hyperpolarization of Em of 8.2 +/- 3.1 mV that lasted at least 60 min. In separate studies, alanine administration did not alter the biliary excretion of a taurocholate load. Taken together, these observations demonstrate that rat hepatocytes in situ are tightly coupled electrically and that physiological stimuli, including fasting, glucagon, and sodium-coupled solute uptake can change Em considerably over time. The late hyperpolarization of Em caused by alanine appears to offset the rise in intracellular Na+ associated with alanine uptake and preserve the Na+ electrochemical gradient such that Na+-coupled taurocholate transport is maintained.

XIV.—Notes on the Atmospheric Electrical Potential Gradient in the Industrial Districts around Leeds

1914 ◽  
Vol 34 ◽  
pp. 202-207
Author(s):  
W. Steuart ◽  
Ingvar Jörgensen
Keyword(s):  
Electrical Potential ◽  
Potential Gradient ◽  
Negative Ions ◽  
Industrial Districts ◽  
General Effect ◽  
Positive Potential ◽  
Electrical Potential Gradient

SUMMARYThe general effect of products of combustion would be to cause a transformation of the small ions of the air into large ions, which, acting alone, would tend to decrease the air conductivity. Ionisation by flames, however, adds to the number of ions in the air, so that the size of the ions might be increased without the conductivity of the air diminishing. In the case of the fresh smoke direct from the forge or colliery chimneystalks or railway engines of our experiments, it is suggested that combustion in the furnaces would result in an ionisation producing more positive than negative ions. It is only where similar conditions obtain that we should expect such large increases in the positive potential Gradient, due to smoke, as we have recorded.

Membrane transport processes in the presence of an applied electrical potential gradient parallel to the aqueous∣membrane interface

2001 ◽  
Vol 496 (1-2) ◽  
pp. 118-123 ◽  
Author(s):  
Nobuhiro Kurauchi ◽  
Yumi Yoshida ◽  
Nobuyuki Ichieda ◽  
Hiroyuki Ohde ◽  
Osamu Shirai ◽  
...  
Keyword(s):  
Membrane Transport ◽  
Electrical Potential ◽  
Potential Gradient ◽  
Transport Processes ◽  
Membrane Interface ◽  
Electrical Potential Gradient

scholarly journals Atmospheric electricity over the ocean

1911 ◽  
Vol 85 (577) ◽  
pp. 175-199 ◽  
Keyword(s):  
New Zealand ◽  
Atmospheric Electricity ◽  
Electrical Potential ◽  
Potential Gradient ◽  
Closed Vessel ◽  
Excellent Opportunity ◽  
Free Ions ◽  
Terra Nova ◽  
Electrical Potential Gradient

Although the different phenomena of atmospheric electricity have been thoroughly investigated over land, very little work has yet been done over the ocean, and on the few occasions on which experiments have been made, the observations have been too few to give conclusive results. It was thought that the long voyage from England to New Zealand of Captain Scott’s Antarctic ship “Terra Nova” would furnish an excellent opportunity for continuing these investigations. The plan of the work to be undertaken was:— (1) To investigate the electrical potential-gradient existing over the ocean. (2) To investigate the quantity of the radioactive products in the air. (3) To measure the number of free ions over the ocean. (4) To investigate the ionisation of the air in a closed vessel, with the object of determining the presence or absence of a penetrating radiation over the sea.

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