Control of Arterial Hypertension by the AhR Blocker CH-223191: A Chronopharmacological Study in Chronic Intermittent Hypoxia Conditions

Chronic intermittent hypoxia (CIH) is a major contributor to the development of hypertension (HTN) in obstructive sleep apnea (OSA). OSA subjects frequently display a non-dipping pattern of blood pressure (BP) and resistant HTN. After discovering that AHR-CYP1A1 axis is a druggable target in CIH-HTN, we hypothesized that CH-223191 could control BP in both active and inactive periods of the animals, recovering the BP dipping profile in CIH conditions. We evaluated the chronopharmacology of the antihypertensive efficacy of the AhR blocker CH-223191 in CIH conditions (21% to 5% of O2, 5.6 cycles/h, 10.5 h/day, in inactive period of Wistar rats). BP was measured by radiotelemetry, at 8 am (active phase) and at 6 pm (inactive phase) of the animals. The circadian variation of AhR activation in the kidney in normoxia was also assessed, measuring the CYP1A1 (hallmark of AhR activation) protein levels. Despite drug administration before starting the inactive period of the animals, CH-223191 was not able to decrease BP during the inactive phase, in CIH conditions, therefore not reverting the non-dipping profile. These results suggest that a higher dose or different time of administration of CH-223191 might be needed for an antihypertensive effect throughout the 24-h cycle.