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Effects of potassium cyanide, strophanthin or sodium‐free perfusion fluid on the electrical potential difference across the guinea‐pig placenta perfused in situ
Author(s) -
Štulc J.,
Švihovec J.
Publication year - 1973
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.1973.sp010240
Subject(s) - potassium , perfusion , sodium , in situ , guinea pig , chemistry , placenta , strophanthin , medicine , cyanide , biophysics , potassium cyanide , endocrinology , fetus , biology , ouabain , pregnancy , inorganic chemistry , organic chemistry , genetics
1. The possible role of active transport of Na in generating the transplacental potential difference (p.d.) was studied in the guinea‐pig placenta perfused in situ by testing the effects of strophanthin or KCN added to the perfusate or of Na‐free perfusion fluid. 2. The p.d. across the perfused placenta was about −20 mV, and was relatively steady during perfusion. 3. Strophanthin (10 −5 M ) slightly increased the p.d. In a concentration of 2 × 10 −6 M strophanthin was without significant effect. 4. KCN (10 −3 M ) decreased the p.d. When KCN was removed after a 30 min treatment the p.d. increased significantly exceeding the initial level. KCN (10 −4 M ) slightly increased the p.d. 5. Perfusion with Na‐free fluid decreased the p.d. to a steady level of about 50–60% of the control values. 6. Perfusion with Na‐free fluid containing KCN (10 −3 M ) for 30 min decreased the p.d. However, the effect did not seem different from the effect of KCN (10 −3 M ) or Na‐free fluid alone. When KCN was removed the p.d. significantly increased in spite of continued perfusion with Na‐free fluid. 7. Excepting the effect of KCN (10 −4 M ), which could not be explained, the observations were found to be consistent with active transport of Na from foetal to maternal side of the placenta as a source of the p.d. The Na transport could account for about 40–50% of the p.d.