The effect of tamsulosin on the response of the rabbit bladder to partial outlet obstruction.
OBJECTIVE
To determine if tamsulosin treatment prevents or decreases the incidence and severity of outlet obstruction-induced bladder dysfunction in rabbits.


METHODS
Male New Zealand White rabbits were treated with tamsulosin or vehicle for 4 weeks with treatments initiated 1 week prior to sham or obstruction surgery. Cystometry was done on anesthetized rabbits 21 days after surgery. The bladders were then removed, weighed, and prepared for in vitro whole bladder studies. Responses to 32 Hz field stimulation (FS), carbachol, phenylephrine, and KCl were measured.


RESULTS
Obstruction resulted in a significant increase in bladder weight, which was unchanged by tamsulosin treatment and a significant increase in micturition pressure in the vehicle-treated group but not in the tamsulosin-treated group. Compliance was significantly decreased in both obstructed groups. The vehicle-treated obstructed rabbits had a very sharp increase in intravesical pressure as the bladder reached capacity; this was not seen in the tamsulosin-treated obstructed rabbits. Tamsulosin did not change the pattern of modifications in contractile responses induced by bladder outlet obstruction.


CONCLUSIONS
In vitro responses of vehicle and tamsulosin-treated obstructed rabbit groups in this study were similar. A greater micturition pressure was found for the vehicle-treated obstructed group than for the tamsulosin-treated obstructed group, which was probably due to decreased urethral resistance in the latter. On a functional basis, the higher compliance at capacity and decreased micturition pressure in the tamsulosin-treated obstructed group would be considered beneficial for bladder function.
Levin
Robert M
RM
Albany College of Pharmacy, Leiderdorp, Albany, New York, NY 12208, USA. levinr@acp.edu
Longhurst
Penelope A
PA
Whitbeck
Catherine
C
Korstanje
Cees
C
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009929:Organ Size / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D013449:Sulfonamides / Q000494:pharmacology*; D000077409:Tamsulosin; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology*; D001748:Urinary Bladder Neck Obstruction / Q000188:drug therapy / Q000503:physiopathology*
D000317:Adrenergic alpha-Antagonists; D018721:Muscarinic Agonists; D013449:Sulfonamides; D011189:Potassium Chloride; D002217:Carbachol; D000077409:Tamsulosin