Electroncytochemical studies on changes of the adenylcyclase activity following experimental hypoxia and ischaemia in perfused rat hearts.

Changes in activity and localization of adenylcyclase were studied in rat heart perfused according to LANGENDORFF after N2-and CO-hypoxia and ischaemia. Under hypoxic conditions an increase of adenylcylase activity was found in the first minutes. Following 3 h nitrogen or 30 min CP perfusion the intensity of reaction was diminished. This later decrease of reaction intensity was not encountered under ischaemic conditions. Changes in localization were not observed either in hypoxia or in ischaemia. After reserpine or propranolol pre-treatment the posthypoxic/ischaemic initial activity-increase did not occur. It is assumed that the early increase in adenylcyclase activity (reaction intensity) following hypoxia/ischaemia is due to endogenous catecholamine release.