Impact of myocardial infarction on cardiac autonomic function in diabetic rats

Abstract Aims We evaluated autonomic and hemodynamic parameters and maximal oxygen consumption (VO2 max) as possible determinants of mortality in streptozotocin (STZ) diabetic rats after myocardial infarction (MI). Method Male 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. VO2 max was measured at 3 (basal), 30, 60, and 91 days after MI. Hemodynamic and autonomic parameters were evaluated 92 days after MI. Results MI 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 VO2 max reductions were observed in the DI compared with the I group. Conclusions Our data suggest that the CO and PVR changes as well as VO2 max reduction were probably associated with additional cardiac autonomic control impairment, and, consequently, increased mortality rate in diabetic rats after a chronic myocardial infarction.