Increased norepinephrine content in diabetic rat heart.

In an attempt to clarify the mechanism of cardiac neuropathy in diabetes mellitus, Wister male rats were made diabetic by streptozotocin injection for 11 to 13 weeks, and catecholamine concentrations of hearts were determined by high performance liquid chromatography. No apparent histological changes were found in hearts and kidneys of any group of rats. Controls used were age-matched normal rats and Goldblatt-hypertensive rats, because streptozotocin induced diabetic rats appeared to be significantly hypertensive. Heart norepinephrine concentrations of diabetic rats and diabetic-Goldblatt-hypertensive rats were markedly higher (8,380 +/- 300 pmol/g tissue and 6,980 +/- 390, respectively) compared with those of controls and Goldblatt-hypertensive rats (2,700 +/- 470 and 2,010 +/- 300, respectively). These results suggest some disturbances in catecholamine secretion in diabetic hearts before typical microangiopathic changes take place.