Aim: to investigate the influence of some stress factors in endothelin-1-induced hypertension.
Material and methods: The experiment was carried out on Wistar rats, treated intraperitoneally, for 4 weeks, as follows: Group 1: saline solution (0.5 ml/100 g weight); Group 2: saline solution + stress; Group 3: Endotelin-1; Group 4: Endotelin-l + stress; Group 5: Endotelin-1 + cholesterol diet (0.2 g/kbw/day); Group 6: Endotelin-1 + cholesterol diet + stress. Endotelin-1 0.25 nmol/kbw was initially administered, followed by 0.5 nmol/kbw 15 min later, 2 times/week. Stress-inducing factors were immobilization and water immersion. In the 28th day of the experiment blood pressure was measured and blood samples were taken from the retro-orbitary plexus to assess plasma cortisol, blood count, phagocytic capacity of peripheral neutrophils, and serum complement activity.
Results and discussions: Repeated administration of endotelin-1 determined an increase in blood pressure, statistically significant in stress conditions comparing to non-stressed animals. Our study proved a decrease of plasma cortisol, total leukocyte count, phagocytic capacity of peripheral neutrophils, without significant alterations in serum complement activity.
Conclusions: Chronic exposure to complex stress conditions in rats with endothelin-1-induced hypertension determined a decrease of plasma cortisol levels, effect correlated with elevated blood pressure and decrease in the number and phagocytic function of peripheral neutrophils.