Pharmacological profile of 2-[125I]iodomelatonin-binding site in Syrian kidney and intestine membranes
| Drugs | Ki for Binding of 2-[125I]Iodomelatonin | |||
|---|---|---|---|---|
| MT3 | HEK-hmt1(mt1) | HEK-hMT2 (MT2) | ||
| Kidney | Intestine | |||
| nM | ||||
| 2-Iodomelatonin | 0.6 | 0.2 | 0.013 | 0.014 |
| 6-Chloromelatonin | 2.9 | 2.5 | 0.58 | 0.26 |
| MIA | 5.9 | 5 | >1,000 | >1,000 |
| Acridine orange | 6.9 | 7.6 | >1,000 | >1,000 |
| 5-MCA-NAT | 7.1 | 6.6 | ≈1,000 | ≈4,000 |
| Prazosin | 10.2 | 12.4 | 540 | 5,300 |
| N-acetylserotonin | 20 | 39 | 65 | 140 |
| EIPA | 21 | 65 | >1,000 | >1,000 |
| Melatonin | 54 | 43 | 0.1 | 0.26 |
| Amiloride | 113 | 176 | >1,000 | >1,000 |
| Rolipram | 128 | 141 | >10,000 | >10,000 |
| Cimetidine | 675 | 290 | >10,000 | >10,000 |
| Cibacron blue | ≈10,000 | ≈10,000 | ≈9,000 | ≈9,000 |
| Isoproterenol | >10,000 | >10,000 | >10,000 | >10,000 |
| Idazoxan | >10,000 | >10,000 | >10,000 | >10,000 |
| Phentolamine | >10,000 | >10,000 | >10,000 | >10,000 |
| Octadecynoic acid | >10,000 | >10,000 | >10,000 | >10,000 |
| Tranylcypromine | >10,000 | >10,000 | >10,000 | >10,000 |
Ki values were calculated from IC50 values obtained from competition curves using the method of Cheng and Prusoff (1973). Inhibition of specific binding of 2-[125I]iodomelatonin (0.2 nM) was determined for 10 concentrations of drugs. Ki values represent the means of two to four independent experiments performed in duplicate.