Supplementary file 1_Dose-dependent vitamin D3 supplementation attenuates endothelial dysfunction and renal injury in an obstructive sleep apnea rat model.docx

Vitamin D deficiency, which frequently coexists with OSA, may further amplify this endothelial injury through impaired endothelial nitric oxide synthase (eNOS) regulation and heightened renin-angiotensin-aldosterone system (RAAS) activity; however, the dose-dependent therapeutic potential of vitamin D3 on combined endothelial and renal outcomes in an IH model remains uncharacterized.</p>Methods<p>Fifty-six adult male Sprague-Dawley rats were allocated to seven groups: control, vitamin D-deficient (VDD), VDD with severe IH (SIH-VDD), and four supplementation subgroups receiving high-dose (37.5 μg/kg/day) or low-dose (25 μg/kg/day) cholecalciferol under severe or moderate IH for 14 days.

Serum E-selectin, ICAM-1, ET-1, NO, and PCSK9 were quantified by ELISA. Renal histopathology was assessed on H&E sections by a blinded pathologist. Data were analyzed by one-way MANOVA, univariate ANOVA, and LSD post hoc tests (p < 0.05).</p>Results<p>The SIH-VDD group showed the most severe endothelial activation: peak E-selectin (4.92 ± 0.90 ng/mL), ICAM-1 (201.50 ± 21.55 ng/mL), ET-1 (5.31 ± 0.81 pg/mL), and PCSK9 (213.50 ± 14.71 ng/mL), with the lowest NO (14.88 ± 2.16 μmol/L; all p < 0.001 vs. control).