Functional role of M_2 and M_3 muscarinic receptors in the urinary bladder of rats in vitro and in vivo

摘要

The findings of the present study suggest that both M_2 and M_3 receptors can cause contraction of the rat bladder in vitro and may also mediate reflex bladder contractions in vivo. It is proposed that muscarinic M_3 receptor activation primarily causes direct contraction of the detrusor whereas M_2 receptor activation can contract the bladder indirectly by reversing sympathetically (i.e.β-adrenoceptor)- mediated relaxation. This dual mechanism may allow the parasympathetic nervous system, which is activated during voiding, to cause more efficient and complete emptying of the bladder.