Potentiation of sympathetic neurotransmission in bovine isolated irides by isoprostanes

Catherine A. Opere, S. Olubusayo Awe, L. C. Harris, A. M. LeDay, S. E. Ohia

Research output: Contribution to journalArticle

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Abstract

Isoprostanes (IsoP) are formed by free radical catalyzed peroxidation of arachidonic acid independent of the cyclooxygenase enzyme. In the present study, we examined the effect of IsoP on norepinephrine (NE) release from the bovine isolated iris. Furthermore, we studied the role of IsoP's in hydrogen peroxide (H2O2)-induced enhancement of NE release from this tissue. Isolated bovine irides were prepared for studies of [3H]NE release using the superfusion method. Release of [3H]NE was induced via electrical field stimulation. Both 8-iso-prostaglandin E2 (E2-IsoP) and 8-iso-prostaglandin F (F2-IsoP) produced a concentration-related enhancement of field-stimulated [3H]NE release from isolated bovine irides, an effect that was mimicked by the thromboxane (Tx) receptor agonist, U46619 and by H2O2. The Tx-receptor antagonist, SQ 29548 inhibited responses to E2-IsoP (10 μM) with an IC50 of 370 ± 50 nM. SQ 29548 (10 μM) also blocked the enhancement of electrically-evoked [3H]NE release induced by U46619 (10 μM) but not that caused by H2O2 (300 μM). The Tx synthetase inhibitor, carboxyheptylimidazole (10 μM) prevented the stimulatory effect of E2-IsoP on evoked [3H]NE release without affecting responses induced by H2O2. We conclude that IsoP's can enhance sympathetic neurotransmission in the bovine isolated iris, an effect that can be blocked by a Tx-receptor antagonist. Furthermore, endogenously produced Tx's mediate the stimulatory effect of IsoP's on NE release. However, endogenously generated IsoP's or Tx's are not involved in H2O2-induced potentiation of sympathetic neurotransmission.

Original languageEnglish
Pages (from-to)257-264
Number of pages8
JournalFree Radical Research
Volume35
Issue number3
StatePublished - 2001

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Isoprostanes
Iris
Synaptic Transmission
Norepinephrine
Thromboxane Receptors
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
8-epi-prostaglandin F2alpha
F2-Isoprostanes
Thromboxane-A Synthase
Dinoprost
Prostaglandin-Endoperoxide Synthases
Dinoprostone
Arachidonic Acid
Hydrogen Peroxide
Electric Stimulation
Inhibitory Concentration 50
Free Radicals
Tissue

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

Opere, C. A., Olubusayo Awe, S., Harris, L. C., LeDay, A. M., & Ohia, S. E. (2001). Potentiation of sympathetic neurotransmission in bovine isolated irides by isoprostanes. Free Radical Research, 35(3), 257-264.

Potentiation of sympathetic neurotransmission in bovine isolated irides by isoprostanes. / Opere, Catherine A.; Olubusayo Awe, S.; Harris, L. C.; LeDay, A. M.; Ohia, S. E.

In: Free Radical Research, Vol. 35, No. 3, 2001, p. 257-264.

Research output: Contribution to journalArticle

Opere, CA, Olubusayo Awe, S, Harris, LC, LeDay, AM & Ohia, SE 2001, 'Potentiation of sympathetic neurotransmission in bovine isolated irides by isoprostanes', Free Radical Research, vol. 35, no. 3, pp. 257-264.
Opere, Catherine A. ; Olubusayo Awe, S. ; Harris, L. C. ; LeDay, A. M. ; Ohia, S. E. / Potentiation of sympathetic neurotransmission in bovine isolated irides by isoprostanes. In: Free Radical Research. 2001 ; Vol. 35, No. 3. pp. 257-264.
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