Abstract P225: Time of Food Intake is an Important Determinant of Blood Pressure Circadian Rhythm
Blood pressure (BP) exhibits a 24-hour rhythm. Loss of BP oscillation is associated with significantly higher risk of target organ injuries. However, the mechanisms underlying the BP circadian rhythm remain incompletely understood. While light is a well-established prominent external cue that entrains intrinsic clock and circadian rhythm, recent studies indicate food intake is also an important external cue that can potently entrain intrinsic clocks especially those in peripheral tissues. However, whether BP circadian rhythm is affected by the time of food intake is unknown. If yes, via what mechanisms: are peripheral clocks and vascular functions involved? To address these specific questions, we used 12-14 weeks old male Per2::LUCIFERASE knock-in mice and investigated the effects of a two-week long, 10 hours light phase time restricted feeding (TRF, food only available from ZT2 to ZT 12) on BP circadian rhythm, clock gene oscillations and vascular contractile function. In the TRF group, food intake was initially decreased but gradually recovered to the ad libitum level by day 5. TRF did not alter body weight but significantly decreased non-fasting blood glucose. The BP was monitored continuously using radiotelemetry from 2 days prior to until 14 days after the TRF. Interestingly, the normal 24 hour BP oscillating rhythm transformed to a 12 hour oscillating rhythm by day 3 after TRF. Using LumiCycle, we investigated the clock gene Per2 expression in various isolated tissues. We found that the phase of Per2 luciferase oscillations was significantly shifted in liver and suprachiasmatic nucleus (SCN) containing brain slices, but was not significantly changed in aorta or mesenteric arteries. The oscillation amplitude of Per1 at mRNA level was suppressed in mesenteric arteries. Interestingly, the isometric contractile responses to high potassium depolarization, alpha1 agonist phenylephrine, and 5-HT were significantly suppressed in the abdominal aorta isolated from TRF group compared to those from ad libitum feed group. In summary, our results demonstrate that the time of food intake is an important determinant of blood pressure circadian rhythm. Moreover, time of food intake affects vascular clock gene oscillations and function.
Author Disclosures: W. Su: None. J. Lutshumba: None. Z. Guo: None. M.C. Gong: None.
- © 2015 by American Heart Association, Inc.