Hyperinsulinemic rats are normotensive but sensitized to angiotensin II

Maria E Johansson, Irene J Andersson, Camilla Alexanderson, Ole Skøtt, Agneta Holmang, Goran Bergstrom

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The effect of insulin on blood pressure is debated and an involvement of an activated renin-angiotensin aldosterone system (RAAS) has been suggested. We studied the effect of chronic insulin infusion on telemetry BP and assessed sympathetic activity and dependence of the RAAS. Female Sprague Dawley rats received insulin (2 IU/day, INS, n=12) or insulin combined with losartan (30 mg/kg/day, INS-LOS, n=10), the angiotensin II receptor antagonist, for six weeks. Losartan-treated (LOS, n=10) and untreated rats served as controls (C, n=11). We used telemetry to measure BP and heart rate (HR), and acute ganglion blockade and air-jet stress to investigate possible control of BP by the sympathetic nervous system. In addition, we used myograph technique to study vascular function ex vivo. INS and INS-LOS developed euglycemic hyperinsulinemia. Insulin did not affect BP but increased HR (27 beats/min on average). Ganglion blockade reduced mean arterial blood pressure (MAP) similarly in all groups. Air-jet stress did not increase sympathetic reactivity but rather revealed possible blunting of the stress response in hyperinsulinemia. Chronic losartan markedly reduced 24-hour-MAP in the INS-LOS group (-38 +/- 1 mmHg P<0.001) compared with the LOS group (-18 +/- 1mmHg, P
Original languageEnglish
JournalAmerican Journal of Physiology: Regulatory, Integrative and Comparative Physiology
Pages (from-to)R1240-R1247
Publication statusPublished - 23. Jan 2008

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