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Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
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Effects of adenosine on polymorphonuclear leucocyte function, cyclic 3': 5'-adenosine monophosphate, and

C P Nielson1, R E Vestal

  • 1Veterans Administration Medical Center, Boise, Idaho 83702.

British Journal of Pharmacology
|July 1, 1989
PubMed

Insights

Adenosine inhibits polymorphonuclear leucocyte (PMN) function by increasing cyclic AMP and reducing intracellular calcium during the respiratory burst. This immune cell modulation is receptor-mediated and stimulus-dependent.

Area of Science:

  • Immunology
  • Cellular Biology
  • Pharmacology

Background:

  • Polymorphonuclear leucocytes (PMNs) are crucial immune cells involved in the respiratory burst.
  • Adenosine is a nucleoside with known immunomodulatory effects.
  • Understanding adenosine's impact on PMN function is vital for inflammatory disease research.

Purpose of the Study:

  • To investigate the effects of adenosine on PMN function, specifically intracellular cyclic AMP and calcium levels during the respiratory burst.
  • To elucidate the receptor subtypes involved in adenosine-mediated PMN inhibition.
  • To determine the relationship between PMN activation stimuli and adenosine's inhibitory effects.

Main Methods:

  • Assessed PMN oxygen metabolite generation using adenosine analogues (NECA, L-PIA).
  • Measured intracellular cyclic AMP levels in response to various PMN activators (calcium ionophore, chemotactic peptide, OAG).
  • Quantified intracellular calcium changes using the fluorescent probe indo-1.

Main Results:

  • Adenosine analogues inhibited PMN oxygen metabolite generation, with potencies suggesting A2 receptor involvement.
  • Adenosine increased intracellular cyclic AMP irrespective of the activation stimulus.
  • Adenosine suppressed intracellular calcium increases when PMNs were activated by calcium ionophore or chemotactic peptide, but not OAG.

Conclusions:

  • Physiological adenosine concentrations inhibit the PMN respiratory burst.
  • This inhibition is associated with increased intracellular cyclic AMP and reduced intracellular calcium.
  • Adenosine's effect on PMN respiratory burst is dependent on the specific activation pathway involved.

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