Impaired β-adrenoceptor mediated venodilation in patients with diabetes mellitus

Aims We investigated whether venoconstriction by α-adrenoceptor stimulation, and venodilation by β-adrenoceptor stimulation and nitroglycerin are altered in patients with diabetes mellitus (DM). Methods Eight male patients with non insulin-dependent DM and eight age-matched control subjects were included. The patients had neither hypertension nor hyperlipidaemia. Noradrenaline (1 to 512 ng min^-1  ), isoprenaline (1 to 256 ng min^-1  ) and nitroglycerin (0.5 to 128 ng min^-1  ) were infused into 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 min^-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 α-adrenoceptor stimulation and venodilation by nitroglycerin are not altered, whereas venodilation by β-adrenoceptor stimulation might be impaired in patients with DM.