Search PubMed⌕ Search

Biomedical subjects

D A Dick

Publications and source records attributed to D A Dick.

43 records · Page 3Linked to original sources
PubMed1968

The action of ethacrynic acid on sodium efflux from single toad oocytes.

1. Ethacrynic acid (10(-3)M) at pH 7.4 caused approximately 83% inhibition of Na efflux from single dissected toad oocytes.2. Less inhibition was found at concentrations below 10(-3)M but higher concentrations did not cause greater inhibition.3. At an external pH of 7.0 the onset of inhibition was more rapid than at pH 7.4.4. Ouabain (10(-3)M) produced only 30% inhibition of the Na efflux, and the subsequent application of ethacrynic acid largely inhibited the remaining efflux.5. Application of ouabain, after ethacrynic acid had produced some 80% inhibition, caused only a further 9% drop in efflux.6. In uninhibited cells, Na efflux was found to be greater at pH 8.0, and less at pH 7.0 than at 7.4.

Animals↗
PubMed1967

Partition of sodium fluxes in isolated toad oocytes.

1. The rate constant for Na efflux from the oocyte calculated from (d/dt) (ln [Na(*)](i)]) is only approximately 52% of that calculated from (d/dt)[(ln(d[Na(*)](i))dt)]. The difference may be interpreted by supposing that 48% of the internal Na of the oocyte is either bound to proteins or sequestered in cell organelles.2. The mean rate constant for Na efflux was 6.4 x 10(-3) min(-1) corresponding to an apparent Na efflux rate of 13.3 p-mole/cm(2).sec. When this is corrected for the increase in surface area produced by microvilli the true efflux rate is 1.1-1.3 p-mole/cm(2).sec.3. The action of ouabain (1-5 muM) appears to involve two different effects: (a) there is 48-65% inhibition of the membrane Na pump, and (b) there is a release of some of the sequestered Na in the cell.4. Removal of external K causes a 40% reduction in Na efflux although this value may be an underestimation owing to the presence of K which has leaked from the cell and may be retained near the cell surface.5. Raising the external K concentration to 15 mM reduces the inhibitory effect of ouabain by approximately a half.6. It was concluded that the Na pump in the toad oocyte may have a slightly lower level of activity than that in frog muscle, but that its general properties are similar to those in frog muscle and some other animal cells.

Animals↗