BLOCKADE OF INTRACELLULAR ACTIONS OF CALCIUM MAY PROTECT AGAINST ISCHEMIC DAMAGE TO THE GERBIL BRAIN

1 The brain cytoprotective effects of a putative calcium-associated protein kinase inhibitor, HA1077, as well as a calcium entry blocker nicardipine were evaluated in models of cerebral ischaemia in Mongolian gerbils. Morphological changes characterizing delayed neuronal death of selectively vulnerable CA1 pyramidal neurones in the hippocampus of the Mongolian gerbil brain occurred 7 days after transient bilateral occlusion of the common carotid arteries. 2 A single injection of HA1077 (1 and 3 mg kg-1, i.p.) 5 min after the occlusion led to a dose-dependent protection of the CA1 neurones. Repeated administrations of HA1077 (1 and 3 mg kg-1, i.p., twice daily for 7 days post-ischaemia) revealed an increase in the number of normal cells, compared to findings with a single administration. 3 In contrast to HA1077, nicardipine (0.3 and 1 mg kg-1, i.p.) did not reduce neuronal degeneration. 4 HA1077 did not interact with the ion channel within which MK-801 binds, as determined by receptor binding. 5 The calcium ionophore, A23187, caused a tonic contraction in canine cerebral arterial strips. HA1077, but not nicardipine, relaxed the A23187-induced contraction, concentration-dependently. 6 These results suggest that blockade of the intracellular actions of calcium may provide protection against ischaemic damage in the brain.