Cardiovascular effects of 2-(O-chlorophenyl)-2-methylaminocyclohexanone (CI-581) in rats.

2-(0-chlorophenyl)-2-methylaminocyclohexanone (CI-581), a derivative of phencyclidine, was shown to depress the cardiovascular system in conscious rats and in rats anaesthetized with pentobarbitone and urethane. In pithed animals, however, there was a substantial rise in blood pressure, suggesting that CI-581 may act on the central cardiovascular regulatory mechanisms. The pressor response to CI-581 in pithed animals was considerably reduced by phenoxybenzamine and phentolamine. In reserpinized animals, the pressor response to CI-581 was abolished but could be restored by infusions with noradrenaline. Thus, CI-581 may act indirectly by releasing catecholamines from peripheral stores. In adrenalectomized rats, the increase in blood pressure elicited by CI-581 was abolished by pre-treatment with reserpine. The data indicate that the peripheral release of catecholamines by CI-581 may be derived from more than one storage site.