[Functional and structural reactivity of the arterial vascular system to angiotensin II in spontaneously hypertensive...

In 55 spontaneously hypertensive rats (SHR) (Okamoto/Aoki) and 63 normotensive Wistar rats (NR) receiving Angiotensin-II, hypertrophically-hyperplastically altered vessels of SHR were tested for their functional and structural reactivity and compared with the behaviour of the arterial vascular system at essential hypertension of man. After 5 days of treatment with 0.15 and 0.02 mg depot-Angiotensin II (A-II) SHR showed an increase in systolic and, with 0.15 mg A-II, even in diastolic blood pressure and bradycardia. At either A-II dosage, plasmatic vasculoses were found at the arterioles and small arteries both in SHR and similarly treated NR, though in higher frequency and in a larger quantity in SHR, as it was the case also with myocardial alterations. Although in the arterial vessels in SHR there developed already primary hypertrophically-hyperplastic wall alterations, A-II application led to functional and structural reactions. Consequently, an additional vasoconstrictor stimulus does not lead in SHR to a process comparable with essential hypertension in man, but merely to reversible, acute vasculopathies.