Norepinephrine release is reduced in cardiac tissue of Type 2 diabetic patients

Aims/hypothesis. The aim of this study was to assess whether cardiac catecholamine release is affected in patients with Type 2 diabetes mellitus. Methods. A trial tissue was obtained from 19 diabetic (Type 2) and 43 non-diabetic patients undergoing coronary surgery. Endogenous norepinephrine release was examined under baseline conditions as well as during electrical field stimulation (effective voltage 5 V, stimulation frequency 4 Hz, pulse width 2 msec) by high performance liquid chromatography and electrochemical detection. Cardiac function and arterial blood pressure was assessed from coronary angiography. Results. In atrial tissue from diabetic patients, stimulation-induced norepinephrine release was reduced by 25% compared with non-diabetic patients, while baseline norepinephrine release did not differ between both groups. Preoperative plasma glucose and haemoglobin A_1C concentrations were increased in patients with diabetes, however, no relation was found to catecholamine release. Diabetic and non-diabetic patients did not differ regarding left ventricular ejection fraction and arterial blood pressure. Conclusion/interpretation. Cardiac norepinephrine release is suppressed in patients with Type 2 diabetes which could contribute to sympathetic neuropathy. The difference of norepinephrine release in diabetic and non-diabetic patients was independent of cardiac function and arterial blood pressure.