The association between nitric oxide synthase (eNOS and iNOS) status, oxidative stress, and cardiac function was evaluated in streptozotocin (STZ)-diabetic rats to understand the etiology of diabetic cardiomyopathy. Cardiac function was determined by echocardiography. eNOS and iNOS status and superoxide production were assessed by immunohistochemistry and chemiluminescence, respectively. In STZ-diabetic rats, stroke volume, cardiac output, and left ventricular ejection fraction were significantly lower than in controls (CT, P < .05), whereas left ventricular end-systolic volume was higher. Cardiac NOS activity increased from 161 +/- 18 cpm/mg tissue in CT rats to 286 +/- 20 cpm/mg tissue (P < .001) in STZ-diabetic rats. Furthermore, superoxide production and cardiac eNOS and iNOS levels were higher in STZ-diabetic rats than in CT rats (P < .05). An increased activation of cardiac eNOS and iNOS is observed concomitantly with decreased cardiac function. Thus, increased oxidative stress in the heart may be implicated in the development of dilated cardiomyopathy in STZ-diabetic rats.
Diabetic patients have a higher incidence of cardiovascular diseases and are more prone to surgical procedures than non‐diabetics. However, there is lack of studies regarding the most appropriate anesthetic induction agent for these patients. In this work, we assessed the cardiovascular effects of the minimal dose required for induction of anesthesia with either propofol (PRO, 50 mg/kg, IP), etomidate (ETO, 20 mg/kg, IP) or ketamine (KET, 100 mg/kg, IP) on Sprague‐Dawley rats 4 weeks after diabetes induction (Streptozotocin, STZ, 65mg/Kg, IP). Age‐matched non‐diabetic rats (CT) were used for comparison. Systolic blood pressure (SBP) and echocardiographic studies including heart rate (HR), stroke volume (SV), and cardiac output (CO) were evaluated. Results demonstrate significant differences between STZ and CT in all studied parameters. KET lowered SBP, SV, HR, and CO in STZ rats by 36.8%, 23.4%, 29.9% and 47.7% respectively when compared to CT (N= 7, P<0.05). In contrast ETO increased SBP by 76.7% (P<0.05) but decreased SV, HR and CO by 17.7%, 34.2% and 48.5% respectively when compared to CT (N= 7, P<0.05). PRO increased SBP by 37.9% (P<0.05) but did not modify HR, SV or CO when compared to CT. These results suggest that diabetes alters the physiological responses to anesthetic induction agents. This study has strong implications for diabetic patients where alterations in their response to these agents are expected.
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