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The role of spinal and peripheral α 1 ‐ and α 2 ‐adrenoceptors on bladder activity induced by bladder distension in anaesthetized rat
Author(s) -
Jeong M.S.,
Lee J.G.
Publication year - 2000
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1046/j.1464-410x.2000.00572.x
Subject(s) - phentolamine , yohimbine , prazosin , doxazosin , cystometry , urination , medicine , distension , reflex , endocrinology , urinary bladder , phenylephrine , anesthesia , urology , stimulation , blood pressure , urinary system , antagonist , receptor
Objective To elucidate the effects of α 1 ‐ and α 2 ‐adrenoceptor antagonists on the micturition reflex induced by bladder distension in the anaesthetized rat at the peripheral and spinal level. Materials and methods Using continuous cystometry in 80 anaesthetized female Sprague–Dawley rats, changes in basal pressure (BaP), micturition pressure (MP), bladder capacity (BC), micturition volume (MV), interval of bladder contraction (frequency) and residual volume (RV) to the selective intra‐arterial and intrathecal administration of drugs were monitored and analysed. Results The intra‐arterial administration of phentolamine, prazosin, doxazosin and tamsulosin significantly decreased the MP; doxazosin increased MV, BC, RV and frequency. MP was inhibited more by intra‐arterial doxazosin than by prazosin or tamsulosin. Intrathecal phentolamine increased BaP, BC, RV and decreased MP and MV; tamsulosin decreased frequency and increased BC. Clonidine markedly increased BaP and frequency, whereas MV and BC were significantly lower; yohimbine increased MV, BC and decreased RV. Intra‐arterial yohimbine significantly increased MV. Conclusions At the spinal level, the micturition reflex evoked by bladder distension was preferentially suppressed by phentolamine or yohimbine, suggesting the involvement of α 2 ‐adrenoceptors. In the periphery, α 1 ‐adrenoceptor blockers preferentially suppressed the reflex. We suggest that both α 1 ‐ and α 2 ‐adrenoceptors play a role in the distension‐evoked micturition reflex in the rat.