Phencyclidine, Lysergic Acid Diethylamide, and Mescaline: Cerebral Artery Spasms and Hallucinogenic Activity

Phencyclidine (PCP), lysergic acid diethylamide (LSD), and mescaline all cause potent contraction of isolated basilar and middle cerebral arteries, with LSD being the most potent, followed by mescaline, then PCP. The concentrations that produce near-maximum contraction of cerebral arteries are similar to those found in the blood and brain of people who died from PCP overdoses. Specific receptors for PCP, distinct from those for LSD and mescaline, exist in cerebral arteries and mediate this vasospasm. The calcium antagonist verapamil can prevent and reverse PCP-induced vasospasm, suggesting a potential clinical treatment for PCP intoxication.

Study at a glance

Abstract

Phencyclidine (PCP), lysergic acid diethylamide (LSD), and mescaline produced potent contractile responses on isolated basilar and middle cerebral arteries, where, in terms of potency, LSD > mescaline > PCP. All three drugs produced cerebrovasospasm in a concentration range which parallels that needed for their psychotomimetic and intoxicating actions. Specific receptors for PCP, which subserve contraction and differ from those for LSD and mescaline, are found in cerebral arteries. Concentrations of PCP that produced near-maximum contractile responses on cerebral arteries were similar to those in the blood and brain of human subjects who had died from PCP overdoses. A specific calcium antagonist, verapamil, readily prevented (and reversed) PCP-induced vasospasm. This study provides direct evidence for PCP receptors in cerebral blood vessels, the biologic action of which can be reversed by a calcium antagonist; the clinical use of the latter could prove invaluable in treating PCP-intoxicated victims.