Improved hemodynamic and cardiorespiratory instability with vitamin D supplementation in an obstructive sleep apnea rat models

Vitamin D deficiency is linked to cardiovascular and respiratory instability, particularly during hypoxic stress, such as in obstructive sleep apnea (OSA). However, the mechanisms connecting vitamin D status to hemodynamic and cardiorespiratory responses in hypoxia remain unclear. This study aimed to assess the impact of vitamin D deficiency on hemodynamic (mean arterial pressure and heart rate) and cardiorespiratory (respiratory rate and peripheral oxygen saturation) stability in an OSA experimental model, along with the effects of dose-dependent vitamin D supplementation. Fifty-six adult male Sprague Dawley rats were divided into seven groups: control, vitamin D-deficient, vitamin D-deficient with severe intermittent hypoxia (IH) and supplementation subgroups exposed to varying levels of IH. Vitamin D deficiency was induced through a diet lacking vitamin D for three weeks, followed by oral supplementation at two doses (25 µg/kg/day and 37.5 µg/kg/day) for two weeks. Intermittent hypoxia was simulated for 14 days, and serum 25-hydroxyvitamin D (25OHD) levels were measured using Elisa. Hemodynamic and cardiorespiratory parameters were recorded, and heart, aorta tissue were analyzed. Vitamin D-deficient groups exhibited significantly lower serum 25OHD levels and showed increased mean arterial pressure, heart and respiratory rates, and reduced oxygen saturation under hypoxia. High-dose supplementation improved 25OHD levels and improved physiological measures, particularly in moderate hypoxia subgroups (p = 0.001). Vitamin D deficiency combined with intermittent hypoxia increased mean arterial pressure, heart rate, and respiratory rate, reduced oxygen saturation, and worsened cardiovascular histology. Vitamin D supplementation improved these changes, especially at higher dose, and protected cardiovascular structures. Vitamin D deficiency combined with intermittent hypoxia induces hemodynamic and respiratory instability and causes cardiovascular tissue alterations. Vitamin D supplementation improves physiological parameters, with greater effects at higher dose, and preserves heart and aortic structure in an obstructive sleep apnea rat model.