Blood pressure changes in relation to sodium and calcium status in inducedhyperinsulinemia

Insulin increases renal sodium reabsorption which may contribute to hyperte nsion. However, acute insulin administration may result in vasodilation. Th e aim of the present study was to investigate effects on blood pressure and alterations in ion status during hyperinsulinemia. Blood pressure and seru m sodium and ionized calcium concentrations were measured before and at the end of euglycemic hyperinsulinemic clamp tests performed in 45 patients wi th essential hypertension. Both the systolic and the diastrolic blood press ure decreased, by 4%: (p < 0.05) and 3% (p < 0.05), respectively. Circulati ng ionized calcium concentration increased by 2% (p < 0.001), and the ratio between circulating sodium and ionized calcium concentrations decreased. T he changes in circulating sodium concentration correlated to changes in sys tolic blood pressure (SBP; r = 0.36, p = 0.05). Both ionized calcium concen trations and the ratio between circulating sodium and ionized calcium conce ntrations correlated to changes in SEP during hyperinsulinemia (r = -0.41, p = 0.03, r = 0.56, p < 0.01, respectively). The changes in ion status were not significantly correlated to age, body mass index or insulin sensitivit y. In conclusion, a more pronounced increase in circulating ionized calcium concentration and reduction in the ratio between sodium and ionized calciu m concentrations was associated with a greater blood pressure decline durin g the hyperinsulinemic clamp test when performed in hypertensive patients.