title: Suppression of post-glucose hyperinsulinaemia does not affect blood pressure in either normotensive or hypertensive subjects.
abstract: 1. Hyperinsulinaemia and insulin resistance are thought to be intimately involved in the development of hypertension, but controversy remains as to whether hyperinsulinaemia is a consequence or a cause of hypertension per se, and whether it plays a role in the short-term regulation of blood pressure. 2. We studied six hypertensive patients [blood pressure 161(9)/101(2) mmHg] and seven normotensive control subjects [blood pressure 122(6)/76(4) mmHg], (P < 0.005) using two oral glucose tolerance tests of 3 h duration. In one of these tests the endogenous insulin response was inhibited with subcutaneous octreotide. 3. After placebo, hypertensive patients had slightly but significantly higher blood glucose levels than controls (P < 0.0001), but comparable insulin concentrations (P > 0.5). Plasma noradrenaline levels were consistently lower in the hypertensive group (P < 0.001). Blood pressure did not change in either group during the 3 h after glucose ingestion. 4. Octreotide completely abolished the immediate insulin response to glucose in all subjects (both P < 0.0001) and caused a delayed and significantly increased glycaemic response in both groups (P < 0.0001). There were no significant differences in plasma glucose responses between groups: however, after octreotide, the hypertensive subjects had a greater insulin suppression than the controls (P < 0.02). Octreotide suppressed noradrenaline levels in the normotensive group (P < 0.001); they were also suppressed in the hypertensive group, but just failed to reach significance (P = 0.056). Throughout the study the hypertensive group's noradrenaline levels remained generally lower than those in the control group (P < 0.0001). 5. In this study there were no differences between hypertensive and normotensive subjects in fasting or post-glucose insulin levels, nor any significant change in blood pressure in either group when post-glucose hyperinsulinaemia was suppressed. This argues against insulin playing a direct role in the short-term regulation of blood pressure.
authors.affiliation: Department of Medicine, University of Liverpool, U.K.
authors.forename: M W
authors.initials: MW
authors.lastname: Savage
authors.forename: V
authors.initials: V
authors.lastname: Mohamed-Ali
authors.forename: G
authors.initials: G
authors.lastname: Williams
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003864:Depression, Chemical; D005260:Female; D005947:Glucose; D005951:Glucose Tolerance Test; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000008:administration & dosage / Q000097:blood; D015282:Octreotide / Q000494:pharmacology*; D013004:Somatostatin / Q000031:analogs & derivatives*
chemical_list: D007328:Insulin; D013004:Somatostatin; D005947:Glucose; D015282:Octreotide; D009638:Norepinephrine