On the Mechanism of Hypotensive Actions of β-blockers

Abstract

Effects of β-blockers on the peripheral sympatheic adrenergic nervous system were studied in atropinized pithed rats under curarized condition using the rise of the diastolic blood pressure produced by stimulation of the spinal nerves as a measure. All the three β₁-blockers used (practolol, atenolol and metoprolol) and oxprenolol produced an inhibition of the pressure rise, without producing a significant inhibition of the pressor response to close-arterial injection of noradrenaline. Propranolol failed to produce any inhibition. However, the pressor response to intraarterial noradrenaline was significantly potentiated by this compound.