Inhibition of increased potassium permeability following fertilization of the echinoderm embryo: Its relationship to the initiation of protein synthesis and potassium exchangeability

Joseph T. Tupper

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14 Scopus citations

Abstract

Addition of 10 mM Ba to suspensions of single-cell embryos of the echnioderm Lytechinus results in a depolarization of membrane potential, an increase in membrane resistance, and a reduction of the unidirectional efflux rate coefficient for potassium. All these effects are consistent with a decrease in membrane permeability to potassium ion (PK). Determination of PK in the presence of Ba indicates a 3- to 5-fold decrease in its magnitude as compared to Ba free cells. Ba at concentrations of 0.5 mM or less has no significant effect on PK. Its effect is maximal at approximately 10 mM, and it is completely reversible upon Ba removal. Eggs fertilized and maintained in 10 mM Ba do not undergo the 3- to 4-fold increase in PK which follows fertilization but rather, they maintain values for PK equivalent to or less than those found in the unfertilized egg. This allows one to evaluate the relationship of the normal increase in PK to the increase in the exchangeability of intracellular K and the onset of protein synthesis, both of which occur shortly after fertilization. The results indicate that the onset of protein synthesis and the increased exchange of intracellular K are events which are independent of the increase in PK. Neither is significantly altered by Ba suppression of the PK increase. The results also indicate that active K transport and amino acid transport are unaffected by maintenance of a low PK. Furthermore, inhibition of protein synthesis (greater than 95% with 10-4M emetine) does not prevent the increased exchange of intracellular K or the increase in PK. Active K transport and amino acid transport are also unaffected.

Original languageEnglish (US)
Pages (from-to)332-345
Number of pages14
JournalDevelopmental Biology
Volume38
Issue number2
DOIs
StatePublished - Jun 1974

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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