Abstract
In cats anaesthetized with pentobarbitone sodium or chloralose and injected with phenoxybenzamine or phentolamine, administration of (–)-noradrenaline (5 to 20 μg) produced a fall of blood pressure which resembled in onset and duration that produced by adrenaline under similar conditions. The depressor action of noradrenaline was due mainly to dilatation of the splanchnic blood vessels. This could be abolished by administration of pronethalol, a drug known to block sympathetic β-receptors.