Impact of myocardial infarction on cardiac autonomic function in diabetic rats

AimsWe evaluated autonomic and hemodynamic parameters and maximal oxygen consumption (VO2max) as possible determinants of mortality in streptozotocin (STZ) diabetic rats after myocardial infarction (MI).MethodMale Wistar rats were divided into (n = 8 of each): control sham (CS), diabetes sham (DS), MI (I), and diabetes + MI (DI). MI was induced 15 days after STZ induction. VO2max was measured at 3 (basal), 30, 60, and 91 days after MI. Hemodynamic and autonomic parameters were evaluated 92 days after MI.ResultsMI area was similar in infarcted groups (~ 44%). Mortality rate increased in the DI (70%) compared with I (53%) group. Cardiopulmonary baroreflex, sympathetic (48%) and vagal (33%) tonus, low frequency (LF) band (57%), and LF/high frequency (HF) band ratio (53%) were reduced in DI compared with I animals. Furthermore, cardiac output (CO), peripheral vascular resistance (PVR) impairment, and VO2max reductions were observed in the DI compared with the I group.ConclusionsOur data suggest that the CO and PVR changes as well as VO2max reduction were probably associated with additional cardiac autonomic control impairment, and, consequently, increased mortality rate in diabetic rats after a chronic myocardial infarction.