Octreotide, a somatostatin analog, reduces insulin secretion and increases renal na+ excretion in lean essential hypertensive patients

The influence of insulin on renal Na+excretion is still subject to debate. In order to evaluate the effect of insulin suppression on Na+excretion, 20 never-treated essential hypertensive men and 8 normotensive men were studied. All subjects had a body mass index <27 kg/m2. Both the glucose and the lipid metabolisms were normal. After 2 weeks under normal NaCl intake (120 mEq NaCl daily), either octreotide, a somatostatin analog, or vehicle were infused in a forearm vein during acute volume expansion (0.30 mL/kg/min isotonic saline given intravenously over a period of 30 min). A double-blind randomized cross-over design was followed, and each subject was given both infusions at a 1 week interval. Blood and urine samples were taken at times —60, 0, 30, 60, 90, 120, 180, 240, and 300 min. Our data showed that octreotide significantly lowered insulin levels in both hypertensives (from 12.2 ± 2.4 µ/mL at time 0 to undetectable values at time 30 and 60 min) and normoten- sives (from 11.5 ± 2.8 µ/mL at time 0, to undetectable values at time 30 and 60 min). Compared to saline infusion alone, octreotide significantly increased Na+ excretion in both hypertensives and normotensives (saline + octreotide v saline alone = P <.05 at time 60 and 90 min). In conclusion, octreotide enhanced the natriuretic response to intravenous Na+ load in both hypertensives and normotensives. The increase in urinary Na+ was accompanied by a significant decrease in plasma insulin levels. Am J Hypertens 1993;6:276-281. © 1993 by the American Journal of Hypertension, Ltd.