Cyclic nitric oxide release by human granulocytes, and invertebrate ganglia and immunocytes: nano-technological enhancement of amperometric nitric oxide determination.

Background: Various tissues from vertebrates and invertebrates respond to external signal molecules by rapid release of nitric oxide (NO) mediated by constitutive nitric oxide synthase.

Material/methods: Invertebrate immunocytes were collected from maintained stock and human granulocytes were isolated from leukocyte-enriched blood obtained from the Long Island Blood Services. The invertebrate ganglionic tissue was either extracted or exposed for ex vivo and in vivo evaluation. Nitric oxide release was 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 in vitro release of NO that fluctuated from 969 to 1003 pM, with a mean change in NO of 35 pM/cycle and a mean cycle time of approximately 4 minutes. Basal release of NO/cycle from the ganglia in vivo was increased 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.