Hypotensive action of beta-blocking drugs injected into the cerebral ventricle of the rat.

Pindolol, propranolol, practolol, N-isopropyl-p-nitrophenyl-ethanolamine (INPEA), d and l-alprenolol were injected into the lateral cerebral ventricle of the anaesthetized rat. Except for INPEA, which has no action at the doses used, these various beta-blocking agents produce a dose-related fall in blood pressure. D-alprenolol and practolol seem to be the least active of the hypotensive agents. Our results show some relationship between the beta-blocking potency of the drugs studied and the hypotension induced when they were injected in the lateral ventricle.