Fig 7. Role of BKs in chloro-induced force changes in precontracted mouse ASM.

(A) ACH induced a steady state contraction in a mouse tracheal ring. Following cumulative additions of chloro, additional contractions were observed prior to the relaxations. (B) The same ring was washed and allowed to rest for 40 min. IbTx was then added and the same experiments were performed. The chloro-induced contractions were inhibited, the relaxations were not affected. (C) Averaged net changes in force from 8 experiments. In the absence of IbTx, lower concentrations (31.6 and 100 μM) of chloro induced contractions compared to that in the presence of IbTx. However, the relaxations in the two groups showed no differences. (D, E, F) The identical experiments were performed except that IbTx replaced by pax and similar results were obtained from 9 experiments. * denotes p < 0.05; *** denotes p < 0.001; NS denotes p > 0.05. To calculate the net contractile forces, the ACH-induced peak value was as the reference level, while the total value of ACH- and blocker-induced peak value will be the reference level for relaxant calculation. These data indicate that BKs involve in chloro-induced force alterations.