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The transplacental potential difference as distinguished from the maternal‐fetal potential difference of the guinea‐pig.
Author(s) -
Binder N D,
Faber J J,
Thornburg K L
Publication year - 1978
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1978.sp012481
Subject(s) - transplacental , fetus , potential difference , nernst equation , chemistry , guinea pig , rubidium , placenta , endocrinology , medicine , pregnancy , biology , electrode , potassium , genetics , organic chemistry
1. We measured the differences in electrical potential between mother and fetus in the guinea‐pig. The fetus was 33 +/‐ 2 (S.E. of mean) mV negative with respect to the mother. 2. Salts of bromine, sulphate, rubidium, and lithium were injected into pregnant sows and blood samples were obtained from the sows and their fetuses at various times after injection. The transplacental electrical potentials at which each of these ions would be in electrochemical equilibrium across the placental exchange barrier were calculated from the Nernst equation and the concentrations in maternal and fetal plasmas. 3. The differences in transplacental electrical potential calculated from the steady‐state concentrations of these ions in maternal and fetal plasmas were within 1 mV of zero. 4. These observations are consistent with a very small difference in electrical potential across the placental exchange barrier itself, and the generation of a potential difference between mother and fetus at a site other than the exchange barrier.