Urethral pressure response to alpha-adrenergic agonist and antagonist drugs in anesthetized healthy male cats.

Urethral smooth muscle tone in response to treatment with phenylephrine, a selective alpha 1-adrenergic receptor agonist, and prazosin a selective alpha 1-adrenergic receptor antagonist, was evaluated in 12 anesthetized healthy adult sexually intact male cats. Intravenous administration of prazosin (20 to 30 micrograms/kg of body weight) decreased the average preprostatic and prostatic intraurethral pressure, compared with baseline and postphenylephrine (20 to 30 micrograms/kg) administration, values. Neither prazosin nor phenylephrine administration had an effect on functional urethral length. Results have implications for the pharmacologic management of lower urinary tract disorders in male cats.