RELATIONSHIP BETWEEN INSULINS HEMODYNAMIC-EFFECTS AND INSULIN-MEDIATED GLUCOSE-UPTAKE

Background Insulin resistance and hyperinsulinaemia are associated wit h hypertension. The relationship between insulin's metabolic and haemo dynamic actions has not been fully elucidated however. Methods We inve stigated, using the euglycaemic clamp technique, the relationship betw een insulin-mediated glucose uptake and insulin-induced changes in leg blood flow and cardiac index in 13 healthy subjects. As insulin's eff ects on blood flow are time dependent, studies were performed during a 4-h insulin (50 mU kg(-1) h(-1)) infusion period. Results Mean arteri al pressure during insulin infusion increased (82.9 +/- 6.7 to 89.8 +/ - 7.7 mmHg; P < 0.001), whereas heart rate was unaltered. Leg blood fl ow gradually increased from 1.09 +/- 0.57 to 1.47 +/- 0.67 mL min(-1) dL(-1) during the second hour, and to 1.65 +/- 0.68 mL min(-1) dL(-1) during the fourth hour of the clamp (P = 0.01). Stroke volume index in creased from 56.5 +/- 13.3 to 63.7 +/- 16.3 mL m(-2) (P = 0.004) and c ardiac index from 3.42 +/- 1.02 to 3.73 +/- 1.05 Lmin(-1) m(-2) (P = 0 .04). The insulin-mediated glucose disposal and the increases in leg b lood flow were not correlated during the second hour (r = 0.21, P = 0. 51) but showed a strong correlation during the fourth hour of the clam p (r = 0.88, P < 0.001). Insulin-mediated glucose disposal was not cor related with the increases in cardiac index. Conclusion Thus, insulin- mediated muscle blood flow may be an important contributor to glucose uptake during sustained exogenous hyperinsulinaemia aiming at physiolo gical insulin levels.