EFFECT OF INTERMITTENT INHALATION OF 4% MOLECULAR HYDROGEN ON HAEMODYNAMIC INDICES OF BAROREFLEX REGULATION IN ANIMALS WITH MONOCROTALIN-INDUCED PULMONARY HYPERTENSIONстатья
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Аннотация:Objective:The aim of the study was to investigate the effects of intermittent inhalation of H2 on possible mechanisms of sympathetic involvement in the regulation of systemic blood pressure in experiments using an in vivo model of monocrotaline-induced pulmonary hypertension.Design and method:Wistar males (180-220 g) were injected subcutaneously with monocrotaline (MCT) (60 mg/kg in 60% C2H5OH). The control group (control) was injected with an equivalent volume of MCT solvent only (60% C2H5OH). Animals receiving the injection of MCT and solvent were divided into 4 groups: 2 breathing air (MCT-Air, n=8) and (Control-Air, n=8), 2 breathing air supplemented with 4% hydrogen (MCT-H2, n=8) and (Control-H2, n=8). Inhalations were performed twice in the morning for 2 each, with a 2 h break, at 3-week intervals from the time of daily MCT or solvent administration. On day 20 plastic catheters were implanted into the femoral vein and artery under zolethenyl-xylazine anaesthesia. One day after the parameters of mean (MBP), systolic BP (SAD), diastolic BP (DBP) blood pressure and heart rate (HR) were measured in awake animals and the BP response to sodium nitroprusside (NP) and phenylephrine hydrochloride (PE) administration was tested. The baroreflex ratio (BRR) was calculated as δHR/δMBP.Results:In the MCT-PH groups, intermittent inhalation of H2 administration of PE resulted in the same increase in BP in both groups, 33.2±3.8 mmHg in the MCT-Air and 33.7±4.0 mmHg in the MCT-H2. At the same time, the HR reduction was 97±8 beats/min in the MCT-H2 and 72±10 beats/min in the MCT-Air.With the same BP lowering response to NP administration (16.4±7.4 mmHg in the MCT-Air and 16.5±3.7 mmHg in the MCT-H2), we observed a statistically significant (p<0.05) reduction in the HR response in the MCT-H2, 49±9 beats/min vs. 73±17 in the MCT-Air). This resulted in a non-significant decrease in NP BRR of -3.4±1.1 in the MCT-H2 vs -5.2±2.6 in the MCT-Air. There was no effect of H2 inhalation on other haemodynamic parameters.Conclusions:A reduction in the response of HR increase to NP observed in the MCT-H2 group vs MCT group, indicating a reduction in sympathetic baroreflex influences.