Role of intracellular calcium in peroxide-induced potentiation of norepinephrine release from bovine isolated irides.
1. BAPTA AM (10 microM), thapsigargin (10 microM), ruthenium red (30 microM) and oligomycin (30 microM) inhibited field-stimulated [3H]NE release from 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 [3H]NE release. 3. Ruthenium red prevented (but oligomycin enhanced) H2O2-induced enhancement of evoked [3H]NE release. 4. We conclude that, although intracellular calcium participates in field-stimulation evoked [3H]NE release from bovine isolated irides, only the mitochondrial pool of calcium may be involved in peroxide-induced enhancement of sympathetic neurotransmission.
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Department of Pharmaceutical and Administrative Sciences, Creighton University Health Sciences Center, Omaha, NE 68178, USA.
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D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002417:Cattle; D002614:Chelating Agents / Q000494:pharmacology; D004357:Drug Synergism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism*; D007498:Iris / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D012430:Ruthenium Red / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D002614:Chelating Agents; D004791:Enzyme Inhibitors; D009840:Oligomycins; D012430:Ruthenium Red; D004533:Egtazic Acid; D019284:Thapsigargin; D006861:Hydrogen Peroxide; D000252:Calcium-Transporting ATPases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium; D009638:Norepinephrine