Table 1. Values of IC50 (μmol/L) for the relaxant effect of 17β-estradiol and progesterone on rat aortic contractions induced by BAY (10 nmol/L) and with KCl (60 mmol/L). The influence of potassium channel inhibitors was analysed using the following drugs: the KV channel blocker 4-aminopyridine (4-AP; 2 mmol/L); the BKCa channel blocker tetraethylammonium (TEA; 1 mmol/L); and the KATP channel blocker glibenclamide (GLI; 10 μmol/L). The influence of the blockage of intracellular hormone receptors was analysed using the estradiol receptor antagonists ICI 182,780 (ICI; 1 μmol/L) and the progesterone receptor antagonists mifepristone (30 μmol/L). Each value represents the mean±SEM from the number of experiments shown in brackets.
| AGENTS | 17β-Estradiol | Progesterone |
|---|---|---|
| BAY | 14.24±0.05 (n=6) | 22.33±0.30 (n=5) |
| KCl | 19.54±1.15 (n=9) | 23.04±0.02 (n=9) |
| KCl+TEA | 22.66±2.76 (n=4) | 20.25±1.11 (n=6) |
| KCl+4-AP | 17.14±1.33 (n=7) | 22.60±1.06 (n=6) |
| KCl+GLI | 30.44±2.43 (n=3) | 18.79±2.01 (n=4) |
| KCl+ICI | 16.97±1.26 (n=6) | |
| KCl+Mifepristone | 24.49±1.35 (n=8) |
4-AP, 4-aminopyridine; BAY, (−)-Bay K8644; GLI, glibenclamide; TEA, tetraethylammonium sodium salt; ICI, ICI 182,780.