[Temporally Relationship between Renal Local Clock System and Circadian Rhythm of the Water Electrolyte Excretion].

ABSTRACT

OBJECTIVE: To investigate the relationship of the circadian rhythm of the urine volume and urine electrolytes excretion rate and the daily expression pattern of the clock genes and clock-controlled genes with the water electrolyte transportation circadian pattern in rat kidneys. METHODS: Male adult SD rats were exposed to in a lightdark (1212) cycles. We collected two period urine from zeitgeber time (ZT)0000-ZT1200 (light time,rest period) and ZT1200-2400 (dark time,activity period) and then compared the urinary excretion rates of volume, sodium, potassium, and chloride at light time with those at dark time. Rats were sacrificed every 4 hours throughout a 24-hour day-night cycle. Circadian clock gene CLOCK, BMAL1,Per1,Per2,Cry1,Cry2 and kidney specific clock-controlled gene NHE3,αENaC、NCC,Ptges,V1aR,V2R expression were profiled by real-time quantitative polymerase chain reaction. Data were analysed by a partial Fourier analysis and a stepwise regression technique. RESULTS: Urine volume and urine potassium excretion rate displayed high level at dark time and low at light time in SD rats (P<0.05),and urine sodium and chloride excretion rate also showed the trend(P>0.05).Clock gene CLOCK,BMAL1,Per1,Per2,Cry1,Cry2(P<0.05)and kidney specific clock-controlled gene NHE3, αENaC, NCC, Ptges, V1aR, V2R (P<0.05)mRNA expression showed circadian pattern,and the peak times of the genes were in the dark time. CONCLUSION: Urine volume and urine electrolyte excretion rate which displayed circadian pattern were temporally coupled with the rhythm of expression of clock and clock-controlled genes associated with water electrolyte transportation in rats kidney.