Circadian Blood Pressure Variation in Transgenic Hypertensive Rats

• Published in: Hypertension (Dallas, Tex. 1979) Tex. 1979), 1993-07, Vol.22 (1), p.97-101
• Main Authors: Lemmer, Björn, Mattes, Andreas, Böhm, Manfred, Ganten, Detlev
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Animals, Genetically Modified; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Pressure - physiology; Cardiology. Vascular system; Circadian Rhythm; Disease Models, Animal; Experimental diseases; Heart Rate - physiology; Humans; Hypertension - physiopathology; Infant, Newborn; Male; Medical sciences; Motor Activity - physiology; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley; Renin - physiology
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.hyp.22.1.97

Automatic, around-the-clock blood pressure measurements have increased our understanding of hypertension in humans. Patients with essential hypertension display patterns similar to those observed in nonnotensive subjects, whereas those with secondary hypertension frequently show abnormal circadian rhythms characterized by a failure to reduce blood pressure at night. We have modeled this situation in rats. Nonnotensive Wistar-Kyoto and Sprague-Dawley rats, spontaneously hypertensive rats, and rats made hypertensive by transgenic implantation of the mouse salivary gland renin gene (TGR[mRen-2]27) underwent chronic implantation of a device that telemetrically monitored their blood pressures, heart rates, and motor activities. In either nonnotensive or hypertensive rats, motor activity peaked during the dark phase, indicating that animals from all strains were nocturnal. In both nonnotensive and spontaneously hypertensive rats, the 24-hour blood pressure and heart rate profiles showed peak values during the ratsʼ active phase at night, ie, between midnight and 3 AM. In the transgenic rats, on the other hand, blood pressure values were at maximum during the day around noon, when the rats were in their resting phase. The heart rate of the transgenic rats nevertheless still peaked around midnight. These data suggest that nonnotensive rats and those with primary and secondary hypertension display circadian rhythms of blood pressure and heart rate analogous to those observed in nonnotensive and primary or secondary hypertensive humans, respectively. The TGR(mRen-2)27 strain may be a useful model with which to investigate the mechanisms responsible for alterations in circadian rhythms of blood pressure and heart rate in forms of secondary hypertension.