ACHIEVING BEST PRACTICE

The aim of the study was to determine the effect of insulin on a conduit artery. In a closed-off test seg-ment of iliac artery in vivo in anaethetised pigs, pressure was kept constant. During the first 10 minutes of exposure to hyperinsulinaemic blood, the test segment diameter was 3.63±0.64 mm (mean ± SD). Dilatation occurred after 10 minutes when the test segment diam-eter increased to 3.80±0.62 mm (mean ± SD), p=0.0006, n=10. The increase in diameter with the vehicle for insulin in blood was-0.0775±0.116 mm (mean ± SD, n=6) and with hyperinsulin in blood was 0.165±0.124 mm (mean ± SD, n=10), p=0.0024. Dilatation with hyperinsulin was 0.229±0.116 mm (mean ± SD) versus insulin plus 250 µg/ml of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester hydrochloride (L-NAME), 0.041±0.026 mm (mean ± SD), p=0.0313, n=6. No evidence of arterial constriction was observed in the presence of L-NAME. We conclude that insulin has a direct relaxing effect on the smooth muscle in the wall of conduit artery, mediated by nitric oxide