Background and objective: Chronic intermittent hypoxia (CIH), one of the main features of obstructive sleep apnea (OSA), enhances carotid body-mediated chemoreflex and induces hypertension and breathing disorders. The carbamylated form of erythropoietin (cEpo) may have beneficial effects as it retains its antioxidant/anti-inflammatory and neuroprotective profile without increasing red blood cells number. However, no studies have evaluated the potential therapeutic effect of cEpo on CIH-related cardiorespiratory disorders. We aimed to determine whether cEpo normalized the CIH-enhanced carotid body ventilatory chemoreflex, the hypertension and ventilatory disorders in rats.Methods: Male Sprague-Dawley rats (250 g) were exposed to CIH (5% O 2 , 12/h, 8 h/day) for 28 days. cEPO (20 mg/kg, i.p) was administrated from day 21 every other day for one more week. Cardiovascular and respiratory function were assessed in freely moving animals.Results: Twenty-one days of CIH increased carotid bodymediated chemoreflex responses as evidenced by a significant increase in the hypoxic ventilatory response (F i O 2 10%) and triggered irregular eupneic breathing, active expiration, and produced hypertension. cEpo treatment significantly reduced the carotid bodychemoreflex responses, normalizes breathing patterns and the hypertension in CIH. In addition, cEpo treatment effectively normalized carotid body chemosensory responses evoked by acute hypoxic stimulation in CIH rats. Conclusion:Present results strongly support beneficial cardiorespiratory therapeutic effects of cEpo during CIH exposure.
BACKGROUND: Hypertonia is characterized by increased resting muscle tone. Previous studies have shown that adult patients with hypertonia displayed autonomic imbalance. However, cardiac sympatho-vagal control in infants with hypertonia have not been explored. The main aim was to estimate cardiac autonomic control in infants with hypertonia using heart rate variability (HRV). METHODS: Thirty infants (0-2 years old) were studied. Heart rate (HR) and R-R interval time series were obtained in 15 Control and 15 Hypertonia infants. HRV was analyzed in time and frequency domains. Additionally, non-linear analysis and entropy measurements were performed. RESULTS: Infants with hypertonia showed cardiac autonomic imbalance as evidenced by alterations in HRV, characterized by an increased power spectral density of low frequency (LF) over high frequency (HF) components of HRV. Indeed, a ∼7% increase in LF, and ∼30% reduction in HF, were found in infants with hypertonia vs. control infants. In addition, time domain and non-linear HRV analysis (Root-mean-square of successive normal sinus R-R interval difference, entropy, and R-R interval variability) were all significantly decreased in hypertonia vs. control subjects. CONCLUSIONS: Our results showed that hypertonia infants displayed HRV disturbances, which suggest an alteration in overall autonomic cardiac modulation in infants with hypertonia compared with healthy condition.
Background Deep breathing (DB) and handgrip (HG) exercise -with and without circulatory occlusion (OC) in muscle-, have been shown to have beneficial effects on cardiovascular function; however, the combination of these maneuvers on heart rate (HR) and cardiac sympathovagal balance have not been previously investigated. Therefore, the aim of the present study was to evaluate the effect of simultaneous DB, HG, and OC maneuvers on the sympathovagal balance in healthy women and men subjects. Methods and results Electrocardiogram and ventilation were measured in 20 healthy subjects (Women: n = 10; age = 27 ± 4 years; weight = 67.1 ± 8.4 kg; and height = 1.6 ± 0.1 m. Men: n = 10; age = 27 ± 3 years; weight = 77.5 ± 10.1 kg; and height = 1.7 ± 0.1 m) at baseline and during DB, DB + HG, or DB + HG + OC protocols. Heart rate (HR) and respiratory rate were continuously recorded, and spectral analysis of heart rate variability (HRV) were calculated to indirectly estimate cardiac autonomic function. Men and women showed similar HR responses to DB, DB + HG and DB + HG + OC. Men exhibited a significant HR decrease following DB + HG + OC protocol which was accompanied by an improvement in cardiac autonomic control evidenced by spectral changes in HRV towards parasympathetic predominance (HRV High frequency: 83.95 ± 1.45 vs. 81.87 ± 1.50 n.u., DB + HG + OC vs. baseline; p < 0.05). In women, there was a marked decrease in HR after completion of both DB + HG and DB + HG + OC tests which was accompanied by a significant increase in cardiac vagal tone (HRV High frequency: 85.29 ± 1.19 vs. 77.93 ± 0.92 n.u., DB + HG vs. baseline; p < 0.05). No adverse effects or discomfort were reported by men or women during experimental procedures. Independent of sex, combination of DB, HG, and OC was tolerable and resulted in decreases in resting HR and elevations in cardiac parasympathetic tone. Conclusions These data indicate that combined DB, HG and OC are effective in altering cardiac sympathovagal balance and reducing resting HR in healthy men and women.
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