Table 3.
Inhibitory effects of heparin and Ruthenium Red on CCh-induced contraction mediated by Ca2+ release in tracheal SM permeabilized with β-escin
Percentage of final contraction | ||||
---|---|---|---|---|
Reagent | Dose | CCh response | CaM response | n |
Heparin | 300 μg ml−1 | 0.1 ± 0.3 * | 37.4 ± 6.1 | 4 |
Ruthenium Red | 100 μm | 6.1 ± 4.8 * | 36.5 ± 5.3 | 4 |
Control | 25.3 ± 5.5 | 38.9 ± 4.5 | 4 |
Rabbit tracheal smooth muscle (SM) was permeabilized with β-escin. After loading Ca2+ in pCa 6.3 for 7 min, 3 μm carbachol (CCh) plus 50 μm guanosine triphosphate (GTP) evoked a transient contraction, followed by washing in a relaxing solution, and treatment with A23187 (10 μm) to deplete the intracellular store of Ca2+. At the steady-state contraction at pCa 6.3, calmodulin (CaM, 5 μm) evoked a further contraction at a constant Ca2+ level of pCa 6.3. Final contraction was obtained at pCa 5.0 in the presence of 5 μm CaM. Data are presented as means ± s.e.m., and were compared by Student's t test with the Bonferroni correction for multiple comparisons. A P value of < 0.05
was considered statistically significant.