Abstract
The purpose of this study is to report the effects of long-term stress to the rats on the blood pressure or the spontaneous hypertension, and on pathological changes especially in cardiovascular system. Methods of stress.
Experiment 1: Male Wistar rats were stressed with thrushing unceasingly and harassingly with a bamboo stick for 20 min./day for three and twelve months. Experiment 2: Male Wistar rats were fed by high fat diet and stressed with the same manner as Experiment 1. for two months. Experiment 3: Spontaneously hypertensive rats (SHRs) and normotensive rats (WKYs) were subjected to combination of immobilization and electrical stress for three months.
Results. 1. The blood pressure reached a high value (191±3mmHg) in twelve months in Experiment 1. The development of hypertension was accelerated in stressed SHRs when compared with unstressed SHRs. 2. Organ-body weight ratios of heart, kidney and adrenal gland were increased by stress. 3. Mean values of relative thickness of media to radius of small arteries were increased in heart of stressed group of twelve months in Experiment 1. and in kidney and mesentery of stressed SHRs in Experiment 2. 4. Myocardium of stressed SHRs in Experiment 3. disclosed severe degree of fibrosis.
