Role of spinal and peripheral alpha 2 adrenoceptors in micturition in normal conscious rats.
OBJECTIVE
To explore the potential of alpha 2-adrenoceptors in modulating vesicourethral function at the spinal and bladder levels.


METHODS
Continuous cystometry was performed in normal, conscious rats, and the urodynamic effects of alpha 2-adrenoceptor stimulation and blockade were recorded.


RESULTS
Given intrathecally, the selective alpha 2-adrenoceptor agonist, dexmedetomidine (dex) 3 nmol., decreased micturition pressure, bladder capacity, micturition volume and residual volume. These effects were counteracted by the selective alpha 2-adrenoceptor antagonist, atipamezole 30 nmol. Intrathecally dex 10 nmol. caused total incontinence in 9 of 9 rats. Given intra-arterially near the bladder, dex 6 nmol. Decreased micturition pressure, bladder capacity, micturition volume, residual urine and basal pressure. Atipamezole 30 nmol. intrathecally increased micturition pressure, bladder capacity and residual urine, and decreased micturition volume. Similar effects were obtained when atipamezole 60 nmol. was given intra-arterially. The selective alpha 2-adrenoceptor antagonist, rauwolscine 200 nmol., had effects similar to those of atipamezole.


CONCLUSIONS
The results show that alpha 2-adrenoceptors can modulate micturition in normal conscious rats both at the spinal and the peripheral levels.
Ishizuka
O
O
Department of Urology, Lund University Hospital, Sweden.
Mattiasson
A
A
Andersson
K E
KE
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D003243:Consciousness; D005260:Female; D007093:Imidazoles / Q000494:pharmacology; D007269:Injections, Intra-Arterial; D007275:Injections, Intravenous; D007278:Injections, Spinal; D020926:Medetomidine; D051381:Rats; D017207:Rats, Sprague-Dawley; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D013131:Spine / Q000187:drug effects / Q000502:physiology*; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology*; D014554:Urination / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D007093:Imidazoles; D011942:Receptors, Adrenergic, alpha; C050701:atipamezole; D020926:Medetomidine