Figure 6.

Effects of combination of procaterol and tiotropium on tension and intracellular Ca²⁺ concentration induced by muscarinic activation. (a) A typical sample record of tension (upper side) and F340/F380 (lower side) showing the inhibitory effect of procaterol (1 nM) in the presence of tiotropium (1 nM) against 1 µM MCh-induced contraction; (b,c) Percent inhibition of tension (white columns) and F340/F380 (black columns) in 1 µM MCh-precontracted tissue incubated with 1 nM procaterol (b, n = 5) and 0.3 nM procaterol (c, n = 4) in the presence of tiotropium (1 nM). Left, sum of percent inhibition of tension and F340/F380 by the two agents; Center, expected percent inhibition of tension and F340/F380 calculated by the Bliss independence theory; Right, percent inhibition of tension and F340/F380 with the two agents in combination. PRO, procaterol; TIO, tiotropium; MCh, methacholine; BI, Bliss independence. ** p < 0.01; * p < 0.05.