FIGURE 4.

Calcium chelation with BAPTA-AM suppresses retinal cell death under in vitro and in vivo ischemic conditions. (a) Chemical ischemia induced the intracellular Ca²⁺ content in fluo-4-loaded Neuro2A cells, which was blocked by pretreatment with the calcium chelator BAPTA-AM (10 μM). (b) The rate of ischemia-mediated TUNEL-positive cell death was reduced by ∼56%, after pretreatment with BAPTA-AM (10 μM), compared with untreated control retinas. *p < 0.05. (c) Ischemia-induced caspase-3 activation and PARP cleavage was reduced upon pretreatment with BAPTA-AM (10 μM). (d) Ischemic retinas treated with 20 mM BAPTA-AM displayed different patterns of Ca⁺ ion movement from ischemic retinas. Furthermore, Ca²⁺ chelation with BAPTA-AM reduced the number of TUNEL-positive dead cells, particularly in INL and ONL. (Squares indicate area of retina detected; dotted lines indicate borders of each layer of retina.) (e) Schematic representation showing that in the presence of the calcium chelator, Ca²⁺ ion redistribution was delayed, and diffusion of Ca²⁺ into entire layers of retina was not detected under ischemic conditions, which was associated with decreased TUNEL-positive cell death.