Alternating light/dark cycle affects autonomic modulation in spontaneously hypertensive rats (LB660)

Effect of light-dark cycle shift on autonomic nervous system modulation hasn’t been previously investigated. We studied the effect of alternating light-dark cycle on autonomic biomarkers in spontaneously hypertensive rats (12mold). ECG and blood pressure (BP) were recorded telemetrically. Rats were subjected to a 12:12h light:dark cycle followed by 12:12h dark:light cycle each for five days, this design was repeated three times. Autoregressive model was used to extract rhythmic oscillations of beat-beat interval composed of very low frequency (VLF; 0-0.2Hz), low frequency (LF; 0.2-0.7Hz) and high-frequency (HF; 0.7-4.0Hz). The alternation showed that during light period, alternating light:dark cycle reduced total variance (16.3±5.5 vs 9.65±2.6ms2/Hz) and VLF (5.6±2.3 vs 2.8±0.6) and increased sympathetic modulation (LFnu; 7.34±2.3 to 8.4±0.99), symothovagal tone (LF/HF; 0.08±0.03 vs 0.11±0.01) and systolic BP (179.7±4.9 to 189.3±1.20 mmHg); whereas, during dark period, shifting light cycle increased total...