AUTONOMIC DYSFUNCTION IN SHORT-TERM EXPERIMENTAL DIABETES

Previous data showed that diabetes induced by streptozotocin for 5 day s causes changes in arterial pressure control and baroreflex regulatio n of heart rate in male Wistar rats. The impairment of baroreflex may be related to autonomic neuropathy as described by several investigato rs. The aim of this study was to identify autonomic changes in shortte rm experimental diabetes in rats (induced for 5 days with streptozotoc in 65 mg IP). Intra-arterial blood pressure signals were obtained from 6 control group and 7 diabetic roup rats and processed in a data acqu isition system (CODAS, 1 kHz). Both vagal and sympathetic function wer e assessed through intravenous injections of methylatropine and propra nolol. Streptozotocin induced hyperglycemia (18.9+/-1.8 versus 5.8+/-0 .2 mmol/L) and reductions in mean arterial pressure (102+/-2 versus 11 7+/-3 mm Hg) and resting heart rate (298+/-14 versus 332+/-2 bears per minute). Sodium and potassium levels were not different between group s. The intrinsic heart rate was reduced in the diabetic group (302+/-1 0 versus 398+/-6 beats per minute). This group also exhibited depresse d vagal and sympathetic tone (50% and 22%, respectively), reduction of vagal effect (42%), and no change in sympathetic effect. In conclusio n, early autonomic dysfunction in short-term streptozotocin-induced di abetes seems to be related to changes in arterial pressure and baroref lex control.