Experimental animals
irritability, hypertensive
HYPERTENSION, ESSENTIAL HYPERTENSION
The 16-month-old SPF-class male SHR rats (genetically modified mating spontaneously hypertensive rats recognized worldwide for their genetically stable hypertension, irritability, and startle-prone nature) were utilized for establishing rat models of elderly essential hypertension, and the Wistar-Kyoto (WKY) rats of the same age with the same background was selected as normal controls. These rats (available from Vital River Laboratory Animal Technology Co., Ltd., Beijing, China) were housed in 1/cage at constant temperature (22 °C) and humidity (40-60%) with 12-h alternating light and dark. The rats were fed with conventional commercial rat chow (Laboratory Rodent Diet 5001, purchased from LabDiet, St. Louis, MO, USA) and drinking water.