Dysfunction of the adrenergic system in phosphate depleted rats

Plasma catecholamines and vascular response to noradrenaline were studied in phosphate depleted rats. Phosphate depletion was induced in rats by dietary phosphorus deprivation for 6 weeks. Basal plasma concentrations of noradrenaline, adrenaline and dopamine were elevated in phosphate depleted rats compared to pairfed control rats. After exposure to cold (4° C, 45 min) the rise in plasma catecholamines was much more pronounced in phosphate depleted rats. In the isolated perfused rat heart, the uptake of tritiated noradrenaline was unchanged. In the isolated perfused hindlimb preparation the vascular response to noradrenaline, but not to potassium chloride and argininevasopressin was significantly diminished in phosphate depleted rats. It is concluded that in phosphate depletion sympathetic activity is elevated and vascular response to noradrenaline diminished.