Chronic circadian disruption impairs cardiovascular rhythms and leads to kidney disease in mice
Authors: Pati Paramita , Benjamin Jazmine , Meek Rachel , Rhoads Megan , Colson Jackson , Pollock David , Pollock Jennifer 
Published: May 2023

Shift workers have an increased risk of developing hypertension and reduced kidney function. Disruption of behavioral or environmental circadian rhythms increases cardiometabolic disease risk in humans and animals. We hypothesized that chronic circadian disruption (CCD) impairs cardiovascular rhythms and increases renal injury markers. Male C57BL/6J mice starting at 8-week of age were maintained under a normal light/dark cycle (12-h light, 12-h dark, control) or a CCD protocol (10-h light, 10-h dark, T20) with ad libitum food and water for 10 weeks. T20 mice gained significantly more body weight compared to control mice. Control mice showed a diurnal variation in food intake, while T20 mice had similar food intake during both light and dark phases with more food consumed in the light phase compared to control mice. Mean arterial pressure (MAP), heart rate (HR), and locomotor activity were measured by telemetry after 10 weeks of CCD. MAP between the light and dark periods was significantly different in control mice (12:12 LD), while T20 mice (10:10 LD) lacked diurnal variation (control 119±3 vs.101±2 mm Hg, dark vs. light, respectively, p<0.001; T20 114±13 vs.113±12 mm Hg, dark vs. light, respectively, p=0.86; n=3-4). Control mice showed a diurnal variation in HR, whereas T20 mice did not show a light-dark difference (Control- 584±11 vs. 511±4 bpm, dark vs. light, respectively, p=0.001; T20- 537±14 vs. 526±5 bpm, dark vs. light, respectively, p=0.48; n=3-4). Dark phase HR was significantly decreased in T20 mice (p=0.01, control vs. T20). Control mice had a light-dark difference in activity, while T20 mice lacked diurnal variation in activity with significantly higher activity during the light phase (p=0.04, control vs. T20). Mice were placed in metabolic cages for urine collection during the light (control: ZT0-12; T20: ZT0-10) and dark (control: ZT12-0; T20: ZT10-0) phases. Urinary excretion of renal tubular injury markers albumin, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) were measured (ELISA). Control mice had significantly higher albumin and NGAL excretion in dark vs. light phases, while T20 mice lacked a significant diurnal pattern with significantly elevated albumin and NGAL during the light phase compared to control mice (albumin: control 1.00±0.23 vs. 0.09±0.05 ug/hr dark vs. light, p=0.04, control light vs. T20 light, p=0.04; NGAL: control 1410±223 vs. 89±58 pg/hr dark vs. light, p=0.02, control light vs.T20 light, p=0.04, n=4-6). CCD also blunted the diurnal rhythm of KIM-1 excretion (light cycle, p=0.04, n=3-6). The diurnal variation in sodium and potassium excretion was also lost in T20 mice. These results indicate that CCD impairs cardiovascular rhythms as well as diurnal excretion of electrolytes and renal injury markers, which may increase risk for kidney disease. P01HL136267, AHA 856877 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.