睡眠・サーカディアンリズム機構から見た血圧調節

Morning surge and/or non-dipping type of hypertension have lately attracted considerableattention, because it has greater risk for cardio-or cerebro-vascular accident. Both sleep andcircadian mechanisms have important roles on the blood pressure（BP）control. Our works onthe control of BP by sleep or circadian system are summarized in this review.During REM sleep, even in mice, sleep apnea frequently occurs and BP shows large fluctuationwith spontaneous surges. The apnea is followed by a surge of BP. Acetazolamide, carbonicanhydrase inhibitors, increases the frequency of ventilation and suppresses the increase of BPduring REM sleep. Moderate hyperoxia（50% O2-N2balance）causes the decrease of ventilationfrequency and augments the increase of BP during REM sleep. These data suggest that, duringREM sleep, hypercapnea caused by the impaired ventilation may occur, which induces the increaseof BP via central chemoreceptor reflex.Clock is one of the main circadian-related genes. BP in the Clock mutant mice（Clockm）issignificantly higher than wild type（WT）during the light period. HR in the Clockm is significantlylower than WT during the dark period. Aderenalectomy induces the disappearance of significantdifference in the amplitude of BP and HR between the Clockm and WT. Concentration of plasmaaldosterone in the Clockm is lower than that in WT. On the other hand, plasma vasopressin in theClockm is higher than that in WT. It is possible that the altered function of water balance, whichis caused by the lack of normal Clock gene, may induce the non-dipping circadian profile of BP and HR.Sleep and circadian system have important roles on the cardiovascular function. It is necessaryto continue physiological in-vivo chronic experiments, in order to clarify the interaction betweensleep or circadian system and other factors relating to the cardiovascular diseases, such as TNFalpha,PAI-1 or IL-6 and so on.