Impaired beta-adrenoceptor mediated venodilation in patients with diabetesmellitus

Aims We investigated whether venoconstriction by alpha-adrenoceptor stimula tion, and venodilation by beta-adrenoceptor stimulation and nitroglycerin a re altered in patients with diabetes mellitus (DM). Methods Eight male patients with non insulin-dependent DM and eight age-mat ched control subjects were included. The patients had neither hypertension nor hyperlipidaemia. Noradrenaline (1 to 512 ng min(-1)), isoprenaline (1 t o 256 ng min(-1)) and nitroglycerin (0.5 to 128 ng min(-1)) were infused in to a dorsal hand vein and its diameter was measured using a linear variable differential transformer. Results The venoconstricting response to noradrenaline and the venodilating response to nitroglycerin in DM patients were similar to those in control subjects, while the venodilation by isoprenaline was significantly (P<0.05) smaller in DM patients than in control subjects at the dose of 32 ng min(- 1) or more [32 ng min(-1) 11.5% vs 29.8% (DM vs control subjects), 64 ng mi n(-1) 19.0% vs 40.1%, 128 ng min(-1) 25.2% vs 49.0%, 256 ng min(-1): 34.3% vs 56.7%]. Conclusions These data suggested that venoconstriction by alpha-adrenocepto r stimulation and venodilation by nitroglycerin are not altered, whereas ve nodilation by beta-adrenoceptor stimulation might be impaired in patients w ith DM.