VASOCONSTRICTOR ACTION OF TOLAZOLINE

In cats treated with reserpine and anaesthetized with pentobarbitone sodium the adrenergic blocking drug, tolazoline, caused a rise of arterial pressure which was inhibited by previous administration of phenoxybenzamine. Tolazoline increased the contractions of the isolated papillary muscles of normal cats but not of cats treated with reserpine. Intra-arterial injection of tolazoline into dogs treated with reserpine and anaesthetized with pentobarbitone sodium reduced the blood flow in the coeliac artery. It is considered that, following reserpine, tolazoline has a sympathomimetic vasoconstrictor action.