Sexual dimorphism in
potassium content was found in plasma, kidney, heart and skeletal muscle of CD1 mice. We observed that feeding mice with a K(+)-deficient diet had an uneven and gender-dependent effect on organ weight and tissue
potassium concentrations. Treatment produced a marked decrease in plasma, pancreas and skeletal muscle K(+) levels in both sexes, and a reduction in kidney, liver and heart
potassium concentrations in females. Moreover, K(+) deficiency produced a 2-3-fold increase in the concentrations of cationic
amino acids, such as
arginine and
lysine in both heart and skeletal muscle of the two sexes, a slight increase ( approximately 37%) in renal
arginine in the male mice. The concentrations of these
amino acids in plasma and other tissues in both sexes remained unaltered.
Polyamine levels in heart, liver, skeletal muscle and pancreas from male and female mice were not affected by K(+) deficiency. However, in the male kidney
potassium deficiency was accompanied by an increase of
putrescine and
spermidine concentration, and a reduction of
putrescine excretion into the urine, even though renal K(+) concentration was not significantly affected and
ornithine decarboxylase activity was dramatically decreased. The general lack of correlation between tissue
potassium decrease and the increase in organic
cations suggests that it is unlikely that the changes observed could be related with an attempt of the tissues to compensate for the reduction in cellular positive charge produced by the fall in K(+) content. The mechanisms by which these changes are produced are discussed, but their physiological implications remain to be determined.