RESUMO
The aim of this study was to test the hypothesis that vascular dysfunction in neonatal streptozotocin (n-STZ)-induced diabetic rats could be associated with alterations in blood pressure, hemodynamic profile, and levels of superoxide anion. Diabetes was induced by STZ injection (160 mg/kg, i.p.) in neonate (2-d-old) Wistar rats. Using intravital microscopy the changes in mesenteric arteriolar diameters to vasoconstrictor agent noradrenaline (NA) and the levels of superoxide anion, measured by hydroethidine microfluorography, were determined in anaesthetized control and n-STZ rats. Blood pressure (BP) was determined in anaesthetized and unanaesthetized animals. Heart rate, shear rate, and blood flow velocity were also assessed. n-STZ rats showed, after 8 weeks of STZ injection, increased BP (unanaesthetized animals), hyperactivity to NA, and increased superoxide anion levels. However, heart rate, arteriolar shear rate, and blood flow velocity were unchanged in n-STZ. In conclusion, the results of the current study describe a significant increase in blood pressure, hyperactivity to NA-mediated vasoconstriction, and increased superoxide levels measured by hydroethidine oxidation. Taken together, our findings demonstrate that the compromised ability of mesenteric microvessels to respond properly in n-STZ diabetic rats is associated with several vascular alterations.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Diabetes Mellitus Experimental/metabolismo , Frequência Cardíaca/efeitos dos fármacos , Norepinefrina/farmacologia , Fenantridinas/metabolismo , Superóxidos/metabolismo , Vasoconstritores/farmacologia , Animais , Disponibilidade Biológica , Viscosidade Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Diabetes Mellitus Experimental/fisiopatologia , Indicadores e Reagentes , Masculino , Microcirculação/efeitos dos fármacos , Oxirredução , Ratos , Ratos Wistar , Fluxo Sanguíneo Regional/efeitos dos fármacosRESUMO
The development of recent flow cytometry-based protocols for the diagnosis of canine babesiosis, Babesia gibsoni in particular, has encouraged us to investigate its applicability to detect B. canis-infected erythrocytes as well as optimize the hydroethidine-flow cytometry methodology (HE-FC), using peripheral blood samples from naturally and experimentally infected dogs. Our data demonstrated that HE at 25 microg/ml provided the most outstanding fluorescence profile, able to discriminate between infected and uninfected dogs with no alterations in cell properties such as forward scatter and unspecific fluorescence. The results were expressed as the percentage of positive fluorescent erythrocytes (PPFE) for each individual sample, with 1.53% of PPFE as the cut-off determined between infected and uninfected animals. B. canis-infected erythrocytes during both acute and chronic experimental infection were identified through HE-FC, validating its use for diagnosis purposes in endemic areas for canine babesiosis. In a clinical trial, 22.8% out of 162 dogs showed to be positive to Babesia infection through this approach. Such prevalence was similar to that estimated for altered hematological profiles (HT) < or = 30% (29%), but highly distinct from the prevalence provided by direct blood smear (BS) examination (1.8%) or immunofluorescent assay (IFA) (60.5%). Furthermore, our findings indicate that positive PPFE data was associated with HT < or = 30%, emphasizing that, in clinical practice, the haematocrit should be used as a screening test followed by HE-FC, suitable to confirm hypotheses of canine babesiosis.