Propranolol, but not naloxone, enhances spinal reflex bladder activity and reduces pudendal inhibition in cats.
This study examined the role of β-adrenergic and opioid receptors in spinal reflex bladder activity and in the inhibition induced by pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS). Spinal reflex bladder contractions were induced by intravesical infusion of 0.25% acetic acid in α-chloralose-anesthetized cats after an acute spinal cord transection (SCT) at the thoracic T9/T10 level. PNS or TNS at 5 Hz was applied to inhibit these spinal reflex contractions at 2 and 4 times the threshold intensity (T) for inducing anal or toe twitch, respectively. During a cystrometrogram (CMG), PNS at 2T and 4T significantly (P < 0.05) increased bladder capacity from 58.0 ± 4.7% to 85.8 ± 10.3% and 96.5 ± 10.7%, respectively, of saline control capacity, while TNS failed to inhibit spinal reflex bladder contractions. After administering propranolol (3 mg/kg iv, a β₁/β₂-adrenergic receptor antagonist), the effects of 2T and 4T PNS on bladder capacity were significantly (P < 0.05) reduced to 64.5 ± 9.5% and 64.7 ± 7.3%, respectively, of the saline control capacity. However, the residual PNS inhibition (about 10% increase in capacity) was still statistically significant (P < 0.05). Propranolol treatment also significantly (P = 0.0019) increased the amplitude of bladder contractions but did not change the control bladder capacity. Naloxone (1 mg/kg iv, an opioid receptor antagonist) had no effect on either spinal reflex bladder contractions or PNS inhibition. At the end of experiments, hexamethonium (10 mg/kg iv, a ganglionic blocker) significantly (P < 0.05) reduced the amplitude of the reflex bladder contractions. This study indicates an important role of β₁/β₂-adrenergic receptors in pudendal inhibition and spinal reflex bladder activity.
Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania;
Marc J
MJ
Rogers
Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Urology, The Second Hospital, Shandong University, Jinan, Peoples Republic of China; and.
Zhiying
Z
Xiao
Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania;
Bing
B
Shen
Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania;
Jicheng
J
Wang
Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania;
Zeyad
Z
Schwen
Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania.
James R
JR
Roppolo
Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania.
William C
WC
de Groat
Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania cftai@pitt.edu.
Changfeng
C
Tai
D019342:Acetic Acid / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002415:Cats; D004195:Disease Models, Animal; D004558:Electric Stimulation; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology*; D060525:Pudendal Nerve / Q000187:drug effects* / Q000503:physiopathology; D012018:Reflex / Q000187:drug effects*; D013119:Spinal Cord Injuries / Q000503:physiopathology; D013127:Spinal Nerves / Q000187:drug effects* / Q000503:physiopathology; D013979:Tibial Nerve / Q000187:drug effects / Q000503:physiopathology; D001743:Urinary Bladder / Q000294:innervation*; D014563:Urodynamics / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D009292:Narcotic Antagonists; D009270:Naloxone; D011433:Propranolol; D019342:Acetic Acid
cat; neuromodulation; pudendal; tibial; urinary bladder