Sympathetic inhibition of the urinary bladder and of pelvic ganglionic transmission in the cat.

1. Electrophysiological techniques were utilized to study the mechanisms underlying adrenergic inhibition in the urinary bladder of the cat.2. It has been shown that catecholamines administered by close intraarterial injection or released endogenously by electrical stimulation of the hypogastric nerves elicit two distinct inhibitory responses in the bladder: (1) a direct depression of the vesical smooth muscle and (2) a depression of transmission in vesical parasympathetic ganglia.3. Pharmacological studies revealed that the inhibitory mechanisms were mediated via different adrenergic receptors: beta-receptors on the smooth muscle and alpha-receptors in the parasympathetic ganglia.4. We have been unable, however, to demonstrate that either of these mechanisms is activated by naturally occurring sympathetic firing.