ENDOGENOUS ZINC PROTOPORPHYRIN MODULATE CARBON-MONOXIDE FORMATION FROM HEME - IMPLICATIONS FOR LONG-TERM POTENTIATION, MEMORY, AND COGNITIVE FUNCTION

Carbon monoxide, which is formed endogenously from heme catabolism cat alyzed by heme oxygenase and shares some of the chemical and biologica l properties of nitric oxide, may play a similar role as a widespread signal transduction mechanism for the regulation of cell function and communication. Zinc protoporphyrin, an inhibitor of heme oxygenase, pr events induction of long-term potentiation. Zinc protoporphyrin is an endogenous substance and we suggest that it has a physiological role, by modulating heme oxygenase activity and, therefore, formation of car bon monoxide from heme. This in turn would modulate long-term potentia tion, memory, and cognitive function.