TY - JOUR
T1 - The ionic basis of the membrane potential in the early Asterias embryo
AU - Tupper, Joseph T.
N1 - Funding Information:
The author greatly appreciates the helpful suggestions of Dr. Philip B. Dunham. This work was supported by Grant No. VC-37 from the American Cancer Society and by the Syracuse University Office of Sponsored Programs. Portions of this work have appeared in abstract form elsewhere (Tupper and Saunders, 1971; Tupper and Powers, 1972).
PY - 1972/11
Y1 - 1972/11
N2 - The ionic basis of the resting potential in the fertilized Asterias embryo has been investigated. The response of the membrane potential (as determined by intracellular microelectrodes) to changes in external K concentration was stable and reversible up to 200 mM K. The time course and magnitude of the response observed upon changes in external K is essentially independent of the concentration of external Cl. There is a significant effect of Na ion on the membrane potential, especially at low external K. The response of the membrane potential to changes in external K could be predicted by a form of the constant field equation. Plots of e VF RT versus external K, in conjunction with the constant field equation, allow an estimate of the internal K concentration and the ratio of Na to K permeability ( PNa PK). These plots indicate at this stage of development an internal K concentration of approximately 200 mM and a PNa PK of 0.03.
AB - The ionic basis of the resting potential in the fertilized Asterias embryo has been investigated. The response of the membrane potential (as determined by intracellular microelectrodes) to changes in external K concentration was stable and reversible up to 200 mM K. The time course and magnitude of the response observed upon changes in external K is essentially independent of the concentration of external Cl. There is a significant effect of Na ion on the membrane potential, especially at low external K. The response of the membrane potential to changes in external K could be predicted by a form of the constant field equation. Plots of e VF RT versus external K, in conjunction with the constant field equation, allow an estimate of the internal K concentration and the ratio of Na to K permeability ( PNa PK). These plots indicate at this stage of development an internal K concentration of approximately 200 mM and a PNa PK of 0.03.
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U2 - 10.1016/0012-1606(72)90067-X
DO - 10.1016/0012-1606(72)90067-X
M3 - Article
C2 - 4652269
AN - SCOPUS:0015429811
SN - 0012-1606
VL - 29
SP - 273
EP - 282
JO - Developmental Biology
JF - Developmental Biology
IS - 3
ER -