THE EFFECT OF AN INTRAVENOUS INFUSION OF ALDOSTERONE UPON MAGNESIUM METABOLISM IN THE SHEEP

Abstract

The concentration of Mg, Na and K in the rumen and plasma of each of four sheep has been studied while test solutions were infused into their jugular veins for 8 h. The experiment was designed as a 4 x 4 Latin square with: treatment 1: diet only; treatment 2: diet +5% dextrose infusion; treatment 3: diet +5% dextrose infusion containing aldosterone; treatment 4: diet +5% dextrose infusion containing aldosterone and potassium canrenoate (a specific inhibitor of the action of aldosterone). Rumen and blood samples were collected every hour during the 8 h treatment period and for the subsequent 4 h. Rumen volume and outflow rate were estimated using an intra‐ruminal infusion of [14C]Cr‐EDTA throughout the collection period. The aldosterone infusion significantly (P 〈 0·001) increased the concentration of Mg in the rumen while rumen volume and outflow rate remained unchanged. Plasma concentrations of Mg and K were significantly (P 〈 0·001 and P 〈 0·05, respectively) lower during the aldosterone infusion while plasma Na concentrations did not vary significantly. The results are discussed in relation to hypomagnesaemic tetany. © 1989 The Physiological Society