The Rate of Potassium Exchange of Galactosemia Rat Lenses

Potassium isotope exchange was studied in whole oocytes, with and without ovarian follicles, and in oocyte cytoplasm and nucleus. Cryomicrodissection was used to prevent solute redistribution during nuclear and cytoplasmic separation. Manual follicle removal causes a small decrease in the K+ of the preparation. No effect of follicle removal is seen on 42K+ exchange. Whole oocyte exchange is multiphasic and reflects the presence of two intracellular K+ fractions. One of these fractions is present in both nucleus and cytoplasm. It exhibits first-order exponential kinetics, apparently established at the cell membrane. The second fraction is restricted to cytoplasm and exchanges at an imperceptible rate. The fractions differ in pre- and posthibernation oocytes. These observations clarify the mechanism whereby nuclear/cytoplasmic K+ concentration asymmetries are maintained and the mechanisms responsible for the high K+-activity coefficient previously reported in these cells.

Download Full-text

POTASSIUM EXCHANGE IN RAT VENTRICULAR MYOCARDIUM: its relation to rate of stimulation

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1970.219.3.747 ◽

1970 ◽

Vol 219 (3) ◽

pp. 747-754 ◽

Cited By ~ 36

Author(s):

ES Blesa ◽

GA Langer ◽

AJ Brady ◽

SD Serena

Keyword(s):

Ventricular Myocardium ◽

Potassium Exchange

Download Full-text

Effects of Potassium Fertilizer on Peanuts in Israel

Experimental Agriculture ◽

10.1017/s0014479700021748 ◽

1966 ◽

Vol 2 (4) ◽

pp. 295-298 ◽

Cited By ~ 6

Author(s):

J. Hagin ◽

H. Koyumjisky

Keyword(s):

Free Energy ◽

Correlation Coefficient ◽

Exchangeable Cations ◽

Potassium Content ◽

Potassium Fertilizer ◽

Potassium Fertilization ◽

Significant Yield ◽

Calcium And Magnesium ◽

Potassium Exchange

SummaryResponse to potassium fertilization was tested, over a two-year period, in 24 experimental fields, predominantly in coarse-textured soils. Only two fields showed significant yield increases. Potassium availability was estimated on the basis of (a) the free energy (ΔF) of potassium exchange for calcium and magnesium, (b) the proportion of potassium in total exchangeable cations, and (c) soluble potassium extraction in correlation with the potassium content of the plants. Woodruff's method (ΔF) yielded the best agreement (correlation coefficient r = 0·77). ΔF values showed a sufficient supply of available potassium, which may have accounted for the lack of response to fertilization.

Download Full-text