The cardiovascular system exhibits distinct circadian rhythms in its activity, mainly in blood pressure (BP), heart rate, peripheral resistance etc. Moreover, number of cardiovascular incidents follows a daily rhythm with maximum risk in the morning hours. It is expected that compromised cardiovascular anticipation observed during hypertension and diabetes can lead to higher risk of cardiovascular incidents. The circadian system plays a key role in anticipation of periodic loads from the environment. Circadian expression of clock gene in the master biological clocks localized in the suprachiasmatic nuclei (SCN) of the hypothalamus and in peripheral organs is important for coordinated function of different organs. In our study we determined daily rhythms in clock genes (per2, Bmal1, clock) expression in target organs (heart and kidney) and central brain structures involved in control of the cardiovascular system (SCN, paraventricular nucleus (n), dorsomedial n., n. ambigus, medulla caudalis ventrolateralis, n. tractus solitarii and circumventricular organs, the anteroventral third ventricle and area postrema). As animals models we used rats with streptozotocine induced diabetes and hypertensive rats TGR(mREN-27) with up regulated renin angiotensine system (RAS) exhibiting a "non dipping" BP profile. Our data suggest that up regulated RAS is important for "non dipping" profile of BP. Mechanisms down stream from the SCN are important for the BP rhythmicity but existence of distinct population of angiotensine II sensitive neurons in the SCN that control BP is still not excluded.

Research was supported by grants APVV-20-022704