ROLE OF INTRACELLULAR CALCIUM IN PEROXIDE-INDUCED POTENTIATION OF NOREPINEPHRINE RELEASE FROM BOVINE ISOLATED IRIDES

1. BAPTA AM (10 mu M), thapsigargin (10 mu M), ruthenium red (30 mu M) and oligomycin (30 mu M) inhibited field stimulated [H-3]NE release f rom bovine isolated irides by 54%, 30%, 30% and 26%, respectively. 2. Both BAPTA AM and thapsigargin had no significant effect (P > 0.05) on H2O2-induced potentiation of evoked [H-3]NE release. 3. Ruthenium red prevented (but oligomycin enhanced) H2O2-induced enhancement of evoke d [H-3]NE release. 4. We conclude that, although intracellular calcium participates in field-stimulation evoked [H-3]NE release from bovine isolated irides, only the mitochondrial pool of calcium may be involve d in peroxide-induced enhancement of sympathetic neurotransmission. (C ) 1998 Elsevier Science Inc.