New approach to study of voiding cycle in cat. Preliminary report on pharmacologic studies.

The effect of autonomic active agents were studied on 23 anesthetized cats. The parameters recorded were circular and longitudinal urethral muscles, and bladder muscle contractions and relaxation as well as intravesical pressure during voiding cycles. Cholinergic stimulant (bethanechol) and blockage (atropine) excited or inhibited the bladder muscle and minimally affected the urethra. Alpha-adrenergic stimulant (norepinephrine) in nonatropinized animals produced mild stimulation on the bladder, and longitudinal-circular urethral muscle synergia appeared to be inadequate. In atropinized animals norepinephrine produced the reverse effect, causing marked inhibition. Alpha blockade (phentolamine) disinhibited the receptors mainly in the bladder and improved the urethral synergia. Beta stimulant (isoproterenol) inhibited the bladder and urethral muscles, and beta blockade (propranolol) stimulated the bladder and urethral muscles.