Exposure to stress differential vascular adaptive response in spontaneously hypertensive and Wistar rats: Role of nitric oxide, and prehypertensive and hypertensive states

• Published in: Life sciences (1973) Vol. 79; no. 7; pp. 646 - 653
• Main Authors: Cordellini, Sandra, Novo, Rosangela, Lanza Júnior, Ubirajara
• Format: Journal Article
• Language: English
• Published: Netherlands 10.07.2006
• Subjects: Adaptation, Physiological - physiology; Adrenergic alpha-Agonists - pharmacology; Animals; Aorta - physiopathology; Endothelium, Vascular - cytology; Endothelium, Vascular - physiology; Hemodynamics - physiology; Hypertension - genetics; Hypertension - physiopathology; Male; NG-Nitroarginine Methyl Ester - pharmacology; Nitric Oxide - physiology; Nitric Oxide Synthase Type III - antagonists & inhibitors; Norepinephrine - pharmacology; Rats; Rats, Inbred SHR; Rats, Wistar; Stress, Psychological - physiopathology
• ISSN: 0024-3205
• DOI: 10.1016/j.lfs.2006.02.007

Stress-induced vascular adaptive response in SHR was investigated, focusing on the endothelium. Noradrenaline responses were studied in intact and denuded aortas from 6-week-old (prehypertensive) and 14-week-old (hypertensive) SHR and age-matched Wistar rats submitted or not to acute stress (20-min swimming and 1-h immobilization 25 min apart), preceded or not by chronic stress (2 sessions 2 days apart of 1-h day immobilization for 5-consecutive days). Stress did not alter the reactivity of denuded aorta. Moreover, no alteration in the EC50 values was observed after stress exposure. In intact aortas, acute stress-induced hyporeactivity to noradrenaline similar between strains at both age. Chronic stress potentiated this adaptive response in 6- and 14-week-old Wistar but not in 6-week-old SHR, and did not alter the reactivity of 14-week-old SHR. Maximum response (g) in intact aortas [6-week-old: Wistar 3.25+/-0.12, Wistar/acute 1.95+/-0.12*, Wistar/chronic 1.36+/-0.21*(+), SHR 1.75+/-0.11, SHR/acute 0.88+/-0.08*, SHR/chronic 0.85+/-0.05*; 14-week-old: Wistar 3.83+/-0.13, Wistar/acute 2.72+/-0.13*, Wistar/chronic 1.91+/-0.19*(+), SHR 4.03+/-0.17, SHR/acute 2.26+/-0.12*, SHR/chronic 4.10+/-0.23; inside the same strain: *P < 0.05 relate to non-stressed rat, +P < 0.05 related to acute stressed rat; n = 6-18]. Independent of age and strain, L-NAME and endothelium removal abolished the stress-induced aorta hyporeactivity. The vascular adaptive response to stress is impaired in SHR, independently of the hypertensive state. Moreover, this vascular adaptive response is characterized by endothelial nitric oxide-system hyperactivity in both strains.