Figure 3. The effects of the β₃ specific agonist mirabegron on motor sensory noise in the conscious partially obstructed rat (modifed from reference ¹⁰). (A) Illustrates an original record showing 4 filling and voiding cycles during cystometry in a conscious rat. The micturition contractions are easily seen. The first 2 cycles are under control conditions and the motor component of the motor-sensory system, the non-voiding activity, is apparent. This is more clearly seen in section (B) where the non-voiding activity has been isolated by filtering. The β₃ specific agonist (YM-178, mirabegron) was then added and the effects on the following filling and voiding cycles noted. The drug clearly affects the non-voiding activity but has little effect on the amplitude of the voiding contraction. (Reprinted from reference ¹⁰ with permission). (B) Shows a cartoon proposing how on-voiding activity and micturition activity is generated in the rat. The accepted parasympathetic motor system is there to initiate the large voiding contraction. In addition the system generating and modulating the motor component of the motor-sensory noise behaves as though it had a “pacemaker” controlled by cholinergic (excitatory) and adrenergic (inhibitory) inputs. Afferent fibers (green) respond to the local contractions and stretches sending information related to bladder volume to the CNS.