Effects of prolonged treatment with adrenergic beta-receptor antagonists on blood pressure, cardiovascular design and reactivity in spontaneously hypertensive rats (SHR).

Abstract

AbstractYoung “prehypertensive” SHR were treated with two kinds of β‐adrenergic receptor antagonists from 2 1 / 2 up to 8 months of age. Arterial pressure largely remained at prehypertensive levels and acute cardiovascular responses to “stress” were considerably modified compared to untreated SHR. Quantitative hemodynamic analyses revealed that resistance vessel design exhibited only slight hypertensive changes when related to untreated controls, while the development of left ventricular hypertrophy was far less influenced by the treatment. In part of the group, pressure was followed for another 6 months after treatment, showing only a delayed and modest pressure rise compared with untreated, matched SHR. When instead adult SHR, with “established” hypertension, were similarly treated from 8 up to 10 months of age, resting arterial pressure remained unaffected and the resistance vessels exhibited only modest regression of the hypertensive changes, with signs of a largely preserved increase of vascular wall/lumen ratio, and with negligible regression of cardiac hypertrophy. The results indicate that early, “preventive” treatment of SHR with β‐receptor blockers is of considerable value whichever their exact modes of action, though some regression of vascular changes can be achieved also in established hypertension, particularly in females (Weiss 1974).