Figure 5.

Relaxing effect of a β-adrenergic agonist on pre-contracted in vitro bladder muscle strips. (a) Effects of graded concentrations of isoproterenol (ISO, 0.1 µM, 0.3 µM, 1 µM, and 3 µM) on carbachol (CCH, 3 µM)-induced pre-contraction of a bladder muscle strip were compared between a WT mouse (left) and a P2Y₆-KO mouse (right). CCH was given at the timing of the dotted line. (b) Likewise, the effect of BRL 37344 (BRL, 3 µM and 10 µM) was compared between a WT mouse (left) and a P2Y₆-KO mouse (right). There were no differences between the 2 groups in degree of relaxation induced by either isoproterenol (WT, n = 10 and P2Y₆-KO, n = 12; P = 0.47, repeated measures two-way ANOVA) or BRL 37344 (WT, n = 12 and P2Y₆-KO, n = 10; P = 0.38) (c). Significant difference from 0.1 µM of isoproterenol or 3 µM of BRL 37344: *P < 0.05, **P < 0.01, ****P < 0.0001 (Tukey’s multiple comparisons test for isoproterenol, or Sidak’s multiple comparisons test for BRL 37344). Values are expressed as the mean ± SEM.