Estrous-related variations of blood pressure and heart rate in female rats.
In female rats, several biological variables change with a 4 or 5 day estrous cycle. To clarify whether blood pressure and heart rate show estrous-related changes, we measured three variables, i.e. mean arterial pressure (MAP), heart rate (HR) and spontaneous activity (ACT), using an implantable radiotelemetry transmitter and a computerized data collecting system non-invasively and chronically for more than 2 months. Under a 12-12 light-dark cycle, the three variables revealed clear daily variations and modulations by the estrous cycle which were most pronounced in the proestrous night. During the proestrous night, ACT showed a remarkable increase and a peak in the first half of the night, whereas MAP showed a gradual increase and a peak around midnight, and HR remained low without forming a peak. All modulations by the estrous cycle disappeared following bilateral ovariectomy. It is concluded that daily variations of blood pressure and heart rate are modulated according to the estrous cycle.
Takezawa
H
H
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Hayashi
H
H
Sano
H
H
Ebihara
S
S
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D004971:Estrus / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D008991:Monitoring, Physiologic; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D013686:Telemetry