TY - JOUR
T1 - Anion modulation of calcium current voltage dependence and amplitude in salamander rods
AU - Thoreson, Wallace B.
AU - Stella, Salvatore L.
N1 - Funding Information:
This work was supported by NIH grant EY-10542, the Gifford Foundation (Omaha, NE), the Nebraska Lion’s Eye Research Institute, and a Research to Prevent Blindness Challenge grant to the UNMC Department of Ophthalmology. WBT is the recipient of a Research to Prevent Blindness Career Development Award. We thank Dr. R.F. Miller, University of Minnesota, for his helpful comments on the manuscript.
PY - 2000/3/15
Y1 - 2000/3/15
N2 - Hofmeister anions were used to investigate the ability of Cl- replacement to produce inhibition and a hyperpolarizing activation shift in L-type Ca2+ currents (I(Ca)) of rod photoreceptors. Inhibition of I(Ca) largely followed the Hofmeister sequence: Cl-=Br--3--4 (ClO-4 caused the greatest suppression). Anion-induced hyperpolarizing activation shifts also followed the Hofmeister sequence: Cl---3--4 (ClO-4 caused the largest shift). Agreement with the Hofmeister sequence suggests that these effects are due to anion interactions at the membrane surface. Hofmeister anions also caused similar hyperpolarizing shifts in the voltage dependence of inwardly rectifying cation currents (I(h)) and outward K+ currents (I(K)) consistent with the hypothesis that hyperpolarizing shifts arise from anion effects on membrane surface potential. Sulfate and phosphate inhibited rod I(Ca) and phosphate caused a significant leftward activation shift suggesting these anions are strongly adsorbed to the membrane. Because of the overlap between the physiological voltage range and the lower part of the I(Ca) activation curve, anion effects on amplitude and activation may influence synaptic transmission at the first retinal synapse. Copyright (C) 2000 Elsevier Science B.V.
AB - Hofmeister anions were used to investigate the ability of Cl- replacement to produce inhibition and a hyperpolarizing activation shift in L-type Ca2+ currents (I(Ca)) of rod photoreceptors. Inhibition of I(Ca) largely followed the Hofmeister sequence: Cl-=Br--3--4 (ClO-4 caused the greatest suppression). Anion-induced hyperpolarizing activation shifts also followed the Hofmeister sequence: Cl---3--4 (ClO-4 caused the largest shift). Agreement with the Hofmeister sequence suggests that these effects are due to anion interactions at the membrane surface. Hofmeister anions also caused similar hyperpolarizing shifts in the voltage dependence of inwardly rectifying cation currents (I(h)) and outward K+ currents (I(K)) consistent with the hypothesis that hyperpolarizing shifts arise from anion effects on membrane surface potential. Sulfate and phosphate inhibited rod I(Ca) and phosphate caused a significant leftward activation shift suggesting these anions are strongly adsorbed to the membrane. Because of the overlap between the physiological voltage range and the lower part of the I(Ca) activation curve, anion effects on amplitude and activation may influence synaptic transmission at the first retinal synapse. Copyright (C) 2000 Elsevier Science B.V.
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U2 - 10.1016/S0005-2736(99)00257-6
DO - 10.1016/S0005-2736(99)00257-6
M3 - Article
C2 - 10704928
AN - SCOPUS:0033962803
SN - 0005-2736
VL - 1464
SP - 142
EP - 150
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 1
ER -