scholarly journals Some aspects of the phytotoxic action of fusaric acid on primary Ricinus roots

2011 ◽  
Vol 50 (No. 9) ◽  
pp. 397-401 ◽  
Author(s):  
J. Pavlovkin ◽  
I. Mistrík ◽  
M. Prokop
Keyword(s):  
Membrane Potential ◽  
Electrolyte Leakage ◽  
Fusaric Acid ◽  
Potential Difference ◽  
Simultaneous Exposure ◽  
Root Cells ◽  
Ph Values ◽  
Acid Ph ◽  
Membrane Potential Difference

Fusaric acid, at a concentration of 1mM induced at pH 5.5 an early hyperpolarisation was followed by a marked depolarisation of membrane potential difference. During this time increased electrolyte leakage from the primary Ricinus roots was determined. At higher pH values (6.5 and 8) the depolarisation caused by fusaric acid was immediate without hyperpolarisation observed at pH 5.5. Simultaneous exposure of the roots to P-ATPase activator fusicoccin and fusaric acid (pH 6.5) diminished the hyperpolarising effect of fusicoccin. The present results suggest that the dissociated form of fusaric acid does directly affect particular cell targets (plasmalemma, mitochondria) and viability of root cells decreased with the time of exposure and concentration of fusaric acid.

Effects of Ultraviolet Radiation on the Plasma Membranes of Chara corallina. I The Hyperpolarized State

1976 ◽  
Vol 3 (5) ◽  
pp. 677
Author(s):  
C.J Doughty ◽  
A.B Hope
Keyword(s):  
Membrane Potential ◽  
Ultraviolet Radiation ◽  
Ultraviolet Irradiation ◽  
Plasma Membranes ◽  
Membrane Conductance ◽  
Chara Corallina ◽  
Potential Difference ◽  
Electrogenic Pump ◽  
Chloride Permeability ◽  
Membrane Potential Difference

Effects of 254 nm ultraviolet irradiation on the plasmalemma potential difference and conductance in C, corallina have been further analysed. Following an increase in passive chloride permeability, revealed from previous studies, and which is manifested as a depolarization of membrane potential difference and an increase in membrane conductance, a secondary depolarization was prominent at pH 7 and is attributed to u.v.-induced inhibition of an electrogenic pump. The secondary depolarization was usually accompanied by a decrease in membrane conductance. For doses of u.v. of 1400 J m-2, these effects were almost reversible within about 1 h

Relation of membrane potential to basolateral TEA transport in isolated snake proximal renal tubules

1995 ◽  
Vol 268 (6) ◽  
pp. R1539-R1545 ◽  
Author(s):  
Y. K. Kim ◽  
W. H. Dantzler
Keyword(s):  
Steady State ◽  
Membrane Potential ◽  
Potent Inhibitor ◽  
Basolateral Membrane ◽  
Potential Difference ◽  
Renal Tubules ◽  
K Concentration ◽  
Electrochemical Equilibrium ◽  
Membrane Potential Difference ◽  
Basolateral Membrane Potential

We measured the effects of changes in bath K+ concentration ([K+]) on basolateral membrane potential difference (PD) and [3H]tetraethylammonium (TEA) transport in isolated snake (Thamnophis) proximal renal tubules (25 degrees C; pH 7.4). Increasing bath [K+] from 3 to 65 mM decreased PD from -60 mV (inside of cells negative) to -20 mV and 2-min uptake of [3H]TEA by approximately 25%, indicating that PD influences TEA entry into the cells. Uptake of [3H]TEA was inhibited similarly at both K+ concentrations by unlabeled TEA, indicating that uptake is carrier mediated. Kt (approximately 18 microM) for 2-min uptake of [3H]TEA in 3 mM K+ increased significantly in 65 mM K+, suggesting that the decrease in PD or the increase in [K+] alters the affinity of the transporter for TEA. The steady-state cell-to-bath ratio for [3H]TEA with 3 mM K+ (-60 mV PD) was approximately 16, significantly above the ratio of 10 predicted for passive distribution at electrochemical equilibrium. With 65 mM K+ (-20 mV PD) this ratio decreased to approximately 6, again significantly above the predicted ratio of 2. These data suggest that the PD can account for much, but not all, of the steady-state uptake of TEA. Efflux of [3H]TEA across the basolateral membrane was identical with either 3 or 65 mM K+ in the bath but was almost completely inhibited in either case by tetrapentylammonium, a potent inhibitor of TEA uptake. These data indicate that virtually all TEA transport across the basolateral membrane is carrier mediated and that transport out of the cells is unaffected by PD.

scholarly journals Effects of Temperature on Membrane Permeability to Ions

1970 ◽  
Vol 23 (4) ◽  
pp. 1047 ◽  
Author(s):  
AB Hope ◽  
PA Aschberger
Keyword(s):  
Membrane Potential ◽  
Fresh Water ◽  
Marine Alga ◽  
Single Cells ◽  
Potential Difference ◽  
Varied Temperature ◽  
Effects Of Temperature ◽  
Fresh Water Alga ◽  
Red Marine Alga ◽  
Membrane Potential Difference

The effects of varied temperature on membrane potential difference (p.d.) and resistance were measured in single cells of the green, fresh water alga Ohara oorallina and the red, marine alga Griffithsia pulvinata. The effects of varied temperature on membrane potential difference (p.d.) and resistance were measured in single cells of the green, fresh water alga Ohara oorallina and the red, marine alga Griffithsia pulvinata.

scholarly journals The Rapid Movement of the Bladder of Utricularia Sp

1973 ◽  
Vol 26 (5) ◽  
pp. 1115 ◽  
Author(s):  
PH Sydenham ◽  
GP Findlay
Keyword(s):  
Membrane Potential ◽  
Internal Pressure ◽  
Membrane Resistance ◽  
Potential Difference ◽  
Rapid Movement ◽  
Membrane Potential Difference

The changes which occur in the internal pressure, volume, membrane potential difference (p.d.), and membrane resistance during the firing of bladders of Utricularia sp. are described.

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