BACKGROUND: Various tissues from vertebrates and invertebrates respondto external signal molecules by rapid release of nitric oxide (NO) mediated by constitutive nitric oxidesynthase.MATERIAL/METHODS: Invertebrate immunocytes were collected from maintained stock and human granulocyteswere isolated from leukocyte-enriched blood obtained from the Long Island Blood Services. The invertebrateganglionic tissue was either extracted or exposed for ex vivo and in vivo evaluation. Nitric oxide releasewas measured using a newly developed NO-selective nanoprobe, exhibiting enhanced sensitivity.RESULTS:Evaluation of NO release from the pedal ganglia of the marine bivalve, Mytilus edulis, demonstrated invitro release of NO that fluctuated from 969 to 1003 pM, with a mean change in NO of 35 pM/cycle anda mean cycle time of approximately 4 minutes. Basal release of NO/cycle from the ganglia in vivo wasincreased significantly to approximately 65 pM (P<0.05) with an increase in cycle time to approximately 7 minutes. Exposure of the ganglia to morphine in vivo resulted in a significant increase in NO release and a lack of NO pulsations. The fluctuation in NO release from immunocytes of Mytilus edulis was approximately 27 pM per cycle with a cycle time of 4 minutes whereas human granulocytes release fluctuated approximately 23 pM with a cycle time of 6 minutes.
Conclusions: These data demonstrate that basal release of NO from various tissues is released in a cyclic manner and the cycle time and magnitude is subject to regulation by external stimuli.

Keywords: Electrochemistry, Ganglia, Granulocytes, Immune System, Mussels, Nitric Oxide, Research Support, U.S. Gov