Renal Magnesium Handling Is Not Subject to Developmental Programming

Developmental programming of hypertension, induced by maternal protein restriction, is associated with enhanced urinary excretion of sodium and calcium in the rat. Although calcium and magnesium are reabsorbed via different pathways, renal calcium excretion often parallels magnesium output. Accordingly, the aim of the current study was to assess magnesium handling in rats exposed to a low-protein (LP) diet in utero. Wistar rats were fed a control (18%) or LP (9%) diet throughout pregnancy; offspring were weaned onto standard rat chow and studied at 4 weeks of age. Renal clearance measurements were made in both volume expanded and euvolaemic anaesthetised rats; 24-hour magnesium turnover was also assessed in conscious animals. Plasma and total body magnesium content were measured. Total (U(Mg)V) and fractional excretion (FE(Mg)) of magnesium did not differ between control and LP rats under any of the experimental conditions. Neither plasma nor total body magnesium content differed between control and LP rats. Thus the hypercalciuria of LP rats is not mirrored by an increase in renal magnesium excretion. These data suggest that renal magnesium handling is not affected by developmental programming.