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 de bate. In order to evaluate the effect of insulin suppression on Na+ ex cretion, 20 never-treated essential hypertensive men and 8 normotensiv e 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 unde r normal NaCl intake (120 mEq NaCl daily), either octreotide, a somato statin analog, or vehicle were infused in a forearm vein during acute volume expansion (0.30 mL/kg/min isotonic saline given intravenously o ver a period of 30 min). A double-blind randomized cross-over design w as followed, and each subject was given both infusions at a 1 week int erval. Blood and urine samples were taken at times - 60, 0, 30, 60, 90 , 120, 180, 240, and 300 min. Our data showed that octreotide signific antly lowered insulin levels in both hypertensives (from 12.2 +/- 2.4 muU/mL at time 0 to undetectable values at time 30 and 60 min) and nor motensives (from 11.5 +/- 2.8 muU/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 normo tensives (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 incr ease in urinary Na+ was accompanied by a significant decrease in plasm a insulin levels.