Effect of chagasic anti-M2 muscarinic acetylcholine receptor (mAChR) antibodies on cAMP accummulation in rat and human distal colon
| cAMP (pmol/mg wet weight) | ||
| Additions | Rat | Human |
| None (basal) | 1.43 (0.09) | 1.98 (0.10) |
| PGE1alone | 4.32 (0.35) | 5.60 (0.34) |
| PGE1+chagasic IgG | 1.96 (0.16)5-150 | 2.35 (0.15)5-150 |
| PGE1+normal IgG | 4.05 (0.36) | 5.42 (0.40) |
| PGE1+chagasic IgG + atropine | 3.93 (0.43) | 5.30 (0.39) |
| PGE1+chagasic IgG + M2 peptide | 3.58 (0.39) | 5.10 (0.42) |
| PGE1+anti-M2 peptide IgG | 1.87 (0.22)5-150 | 2.10 (0.17)5-150 |
| PGE1+anti-M2peptide IgG+AF-DX 116 | 3.85 (0.41) | 4.95 (0.45) |
| PGE1+anti-M2 peptide IgG+M2peptide | 3.94 (0.40) | 5.12 (0.40) |
| PGE1+anti-M2 peptide IgG+PTX | 4.52 (0.35) | 5.78 (0.38) |
3′,5′-Cyclic monophosphate (cAMP) accumulation was measured after incubation of tissues for 15 minutes with 1×10−5M total IgG or 1×10−6 M anti-M2 peptide IgG from chagasic patients with megacolon or IgG from normal subjects. Then, 1×10−6 M prostaglandin E1(PGE1) was added five minutes before the end of the reaction. Inhibitory experiments were performed by incubating tissue for 15 minutes with 5×10−6 M pertussis toxin (PTX), atropine, or AF-DX 116, before IgGs were added. The M2peptide neutralisation experiments were performed by preincubating IgG with the peptide (5×10–5 M) over 30 minutes at 30°C prior to tissue exposition.
Values are mean (SEM) of the IgG fraction from five different chagasic megacolon patients or normal individuals.
↵5-150 Significantly different from PGE1 alone, p<0.0001.