Plasma creatine phosphokinase levels in rats following lysergic acid diethylamide

Lysergic acid diethylamide (LSD) injected intraperitoneally or intramuscularly did not increase rat plasma creatine phosphokinase (CPK) activity. LSD did not produce an increase in serum CPK activity in rats kept in a 2 degrees C environment for 2 hrs. LSD also did not potentiate, in rats, the increase in plasma CPK activity produced by restraint at 2 degrees C or 24 degrees C. It is likely that the increases in serum CPK activity previously reported to occur in people who became psychotic following LSD ingestion are a consequence of the psychotic state itself rather than a direct effect of LSD.