Putative signaling pathways of autonomic nervous responses. Muscarinic cholinergic and beta-adrenergic pathways involved in autonomic nervous system responses of crucian carp atrial myocytes. Activation of muscarinic cholinergic receptors induces IK,CCh and inhibits ICa via βγ and αi/o-subunits of the trimeric G protein, respectively. Inhibition of ICa is dependent on the tonic activation of adenylate cyclase (AC) under basal conditions, i.e. in the absence of agonist binding to beta-adrenergic receptors (β). Nitric oxide synthase (NOS) is not involved in modulating the responses. Cholinergic activation of IK,CCh and inhibition of ICa results in shortening of action potential and depression of atrial contraction force. GIRK, G protein activated inward rectifier potassium channel; LCC, L-type calcium channel; M2, muscarinic cholinergic receptor; PDE2, phosphodiesterase; PKA, protein kinase A.
Vornanen et al. BMC Physiology 2010 10:10 doi:10.1186/1472-6793-10-10