Nongenomic effects of aldosterone on phosphocreatine levels in human calf muscle during recovery from exercise.

Nongenomic in vitro effects of aldosterone on the sodium-proton
antiport and intracellular second messengers have been described in
human mononuclear leukocytes, vascular smooth muscle cells, and
endothelial cells. To test the potential physiological relevance of
these effects, an in vivo 31P magnetic resonance spectroscopy study
on the human calf at rest and during exercise was performed in 10
healthy volunteers receiving either 1 mg aldosterone or placebo iv
in a double blind, randomized, cross-over trial. Spectra were
analyzed for phosphocreatine, ATP, phosphomonoesters, inorganic
intracellular phosphate, and intracellular pH. Resting values
remained unchanged by aldosterone. After isometric contraction of
the calf (50% body weight for 3 min), phosphocreatine recovered to
significantly higher levels after application of aldosterone
compared with placebo. Other parameters were not significantly
changed by aldosterone. Effects appeared immediately after
isometric contraction and, thus, occurred within 8 min of
aldosterone administration. They are, therefore, likely to
represent the first contemporary evidence of nongenomic in vivo
effects of aldosterone in man. These findings also point to an
involvement of aldosteron in the acute stress adaptation of
cellular oxidative metabolism in human muscle physiology.