Abstract
Propranolol readily penetrated all areas of the central nervous system after acute intraperitoneal administration and was cleared within 8–16 hr. Propranolol levels in the heart followed a similar pattern. After chronic oral administration brain levels of propranolol were equal to those 3 hr after intraperitoneal injection. Propranolol caused no significant difference in the brain levels of noradrenaline, normetanephrine, dopamine, 3-methoxytyramine, homovanillic acid, 5-hydroxy-tryptamine or total indoles, nor did it cause measurable changes in rat behaviour. An increase by propranolol in sleeping time after chloral hydrate in rats and mice was observed; this effect could not be correlated with changes in brain amine concentrations.