ALEXANDRE JOSE TAVOLARI ARNOLD
Projetos de Pesquisa
Unidades Organizacionais
LIM/59 - Laboratório de Biologia Celular, Hospital das Clínicas, Faculdade de Medicina
3 resultados
Resultados de Busca
Agora exibindo 1 - 3 de 3
- Early changes in myocyte contractility and cardiac function in streptozotocin-induced type 1 diabetes in rats(2020) MARCHINI, Gustavo S.; CESTARI, Ismar N.; SALEMI, Vera M. C.; IRIGOYEN, Maria Claudia; ARNOLD, Alexandre; KAKOI, Adelia; ROCON, Camila; AIELLO, Vera D.; CESTARI, Idagene A.Diabetes can elicit direct deleterious effects on the myocardium, independent of coronary artery disease or hypertension. These cardiac disturbances are termed diabetic cardiomyopathy showing increased risk of heart failure with or without reduced ejection fraction. Presently, there is no specific treatment for this type of cardiomyopathy and in the case of type I diabetes, it may start in early childhood independent of glycemic control. We hypothesized that alterations in isolated myocyte contractility and cardiac function are present in the early stages of experimental diabetes in rats before overt changes in myocardium structure occur. Diabetes was induced by single-dose injection of streptozotocin (STZ) in rats with data collected from control and diabetic animals 3 weeks after injection. Left ventricle myocyte contractility was measured by single-cell length variation under electrical stimulation. Cardiac function and morphology were studied by high-resolution echocardiography with pulsed-wave tissue Doppler imaging (TDI) measurements and three-lead surface electrocardiogram. Triglycerides, cholesterol and liver enzyme levels were measured from plasma samples obtained from both groups. Myocardial collagen content and perivascular fibrosis of atria and ventricle were studied by histological analysis after picrosirius red staining. Diabetes resulted in altered contractility of isolated cardiac myocytes with increased contraction and relaxation time intervals. Echocardiography showed left atrium dilation, increased end-diastolic LV and posterior wall thickness, with reduced longitudinal systolic peak velocity (S') of the septum mitral annulus at the apical four-chamber view obtained by TDI. Triglycerides, aspartate aminotransferase and alkaline phosphatase were elevated in diabetic animals. Intertitial collagen content was higher in atria of both groups and did not differ among control and diabetic animals. Perivascular intramyocardial arterioles collagen did not differ between groups. These results suggest that alterations in cardiac function are present in the early phase in this model of diabetes type 1 and occur before overt changes in myocardium structure appear as evaluated by intersticial collagen deposition and perivascular fibrosis of intramyocardial arterioles.
- THE EFFECTS OF PYRIDOSTIGMINE BROMIDE ON AUTONOMIC, HEMODYNAMIC AND METABOLIC PARAMETERS IN FEMALE OVARIECTOMIZED C57BL/6 MICE(2018) RIBEIRO, Amanda; SILVA, Maikon; ARNOLD, Alexandre Jose; JENSEN, Leonardo; SANTOS, Fernando; IRIGOYEN, Maria-Claudia
- A method to assess heart rate variability in neonate rats: validation in normotensive and hypertensive animals(2020) FREITAS, S. C. F.; SANTOS, C. Paixao dos; ARNOLD, A.; STOYELL-CONTI, F. F.; DUTRA, M. R. H.; VERAS, M.; IRIGOYEN, M. C.; ANGELIS, K. DeSeveral studies have focused on the heart rate variability (HRV) of murine species, while studies discussing HRV in murine neonates and infants remain scarce, since recording hemodynamic signals through invasive methods in small animals has been found to be quite challenging. Thus, this study aimed at describing and validating a novel method to assess HRV in newborn rats. An electrocardiogram (ECG) system was used to determine RR intervals in awake newborns and evaluate HRV in normotensive (Wistar) and hypertensive (SHR) neonate rats. After birth, ECG was recorded in the awake newborns, and they were allowed to rest on a heated surface, restricted only by the weight of the adhesive ECG electrodes. The electrodes were cut and adapted to provide more comfort to the animal, and gently placed on the newborn's skin. RR intervals were recorded over a 30-min period using an ECG system together with LabChart software (4 KHz). Three sequences of 5 min each from the ECG recording period were analyzed in time and frequency domains, using CardioSeries software. ECG data resulted in a clearly interpretable signal that was used to generate an RR interval sequence through time for the analysis of HRV. SHR neonates presented increased cardiac sympathovagal balance compared to Wistar neonates (low frequency/high frequency: 3.85 +/- 0.71 vs 0.90 +/- 0.09). In conclusion, the ECG setup here described may be used to record RR intervals to assess HRV in neonate rats, thus detecting early impairment of HRV in hypertensive newborns.