Effect of terodiline hydrochloride on the function of urinary bladder in rats

The effect of terodiline on the function of urinary bladder was investigated in anesthetized rats. When saline was infused continuously into the urinary bladder of rats, terodiline (1-10 mg/kg, i.v.) prolonged the time to micturition in a dose-dependent manner. When enough saline was infused into the urinary bladder to induce the voiding contraction in urethra-ligated rats, terodiline (1-10 mg/kg, i.v.) and verapamil (1 mg/kg, i.v.) abolished the contraction, of which amplitude and frequency were partially inhibited by atropine (1 mg/kg, i.v.). Efferent discharge from the pelvic nerve on the micturition reflex was inhibited by terodiline (3 mg/kg, iv.v.). Both of the bladder contractions evoked by the electrical stimulation of the peripheral or central cut end of the pelvic nerve were dose-dependently inhibited by terodiline (1-10 mg/kg, i.v.). At 3 mg/kg or more, terodiline significantly inhibited the contraction, and the effects were long lasting. The effect of atropine (1 mg/kg, i.v.) was similar to that of terodiline (3 mg/kg, i.v.). Increase in frequency of urination and decrease in total urinary volume per micturition after the bilateral transection of the hypogastric nerve were improved after on oral administration of terodiline (1-10 mg/kg).     

Species-related variations in the effects of capsaicin on urinary bladder functions: relation to bladder content of substance P-like immunoreactivity

Summary 1. The effect of capsaicin on bladder motility in vivo (urethane anaesthesia) and in vitro, plasma extravasation (Evans blue leakage technique) and content of substance P-like immunoreactivity (SP-LI) of the urinary bladder was investigated in various mammalian species. 2. Systemic capsaicin desensitization (rat and hamster, 50 mg/kg s.c. 4 days before; guinea-pig 55 mg/kg s. c. 4–7 days before) increased bladder capacity in rats and guinea-pigs and reduced voiding efficiency in guinea-pigs. All other urodynamic parameters were unaffected in both rats, guinea-pigs and hamsters. 3. Reflex bladder voiding was abolished by spinal cord transection in anaesthetized rats and hamsters. On the other hand, hexamethonium-(20 mg/kg i.v.)sensitive voiding contractions were obtained in response to saline filling 45 min from cord transection in guinea-pigs, indicating a profound interspecies variation in the basic organization of micturition. 4. Exposure to capsaicin (1 M) produced a contraction of the isolated bladder from rats, guinea-pigs (dome) and mice. Capsaicin produced only a slight contractile response in the guinea-pig bladder base. The motor response to capsaicin of the rat, guinea-pig and mouse bladder exhibited marked desensitization, suggesting a specific effect on sensory nerves. On the other hand, capsaicin (1 M) produced a slight relaxation of the hamster isolated bladder but this effect was reproducible at 1–2 h intervals, suggesting an unspecific effect. Capsaicin (1–10 M) did not affect motility of strips from the dome or the base of the rabbit bladder. 5. Intravenously administered capsaicin produced a marked plasma extravasation (Evans blue leakage) in the lower urinary tract of rats, mice and guinea pigs. In rats but not guinea-pigs the reaction in the bladder base was greater than in the dome. In hamsters intravenous capsaicin failed to induce any significant Evans blue leakage in the lower urinary tract. 6. SP-LI was detected in the lower urinary tract of rats, guinea-pigs, rabbits and mice but not hamsters. Bladder SP-LI was depleted by systemic capsaicin desensitization in rats, guinea-pigs and mice. Reverse phase HPLC indicated that all the immunoreactive material co-eluted with authentic substance P or its oxidized form. 7. These findings indicate that noticeable species-related differences exist with regard to the functions mediated by the Capsaicin-sensitive neurons in the urinary bladder. Send offprint requests to C. A. Maggi     

In vivo effects of gamma-aminobutyric acid on the urinary bladder contraction accompanying micturition

We studied the effects of the gamma-aminobutyric acid (GABA) receptor agonists, diazepam and muscimol, on the urinary bladder contraction induced by infusion of Tyrode's solution into the bladder in anesthetized rats. Diazepam (1 mg/kg, i.p.) completely inhibited bladder contraction, causing the bladder pressure to rise until solution leaked from the penis. The inhibitory effects of diazepam were reversed by picrotoxin (1 mg/kg, i.v., twice with an interval of 10 min), and the effects were potentiated and attenuated by pretreatment with aminooxyacetic acid (AA, 10 mg/kg, i.v.) and semicarbazide (200 mg/kg, i.v.), respectively. Only pretreatment with AA inhibited the bladder contraction induced by infusion of Tyrode's solution into the bladder in six out of eight rats. Diazepam abolished efferent discharges recorded from the left pelvic nerve, but hexamethonium facilitated the generation of efferent discharges after inhibition of bladder contraction. After complete inhibition of bladder contraction by diazepam, electrical stimulation of the left pelvic nerve at 5 Hz for 30 sec was able to induce bladder contraction, and this resulted in micturition. Intracerebroventricular injection or intrathecal injection into the sacral part of the spinal cord of 1 microgram muscimol completely inhibited the bladder contraction. It was considered that the inhibitory effects of GABA receptor agonists on bladder contraction were mainly induced through the GABA receptors in the micturition center of the sacral cord, as well as the brain stem.     

Excitatory and inhibitory urinary bladder reflexes induced by stimulation of cervicovaginal capsaicin-sensitive sensory fibers in rats

We have investigated the effect of intravaginal application of capsaicin on micturition reflex in female rats. Urinary bladder contractility was measured by transurethral pressure recording at isovolumetric and subthreshold conditions in anaesthetized rats. The intravaginal application of capsaicin (15 mug/50 mul rat) induced reproducible bladder phasic contractions, without desensitization upon repeated applications, that were blocked by intravenous atropine (1 mg/kg) or hexamethonium (5 mg/kg) and prevented by removal of paracervical ganglia or systemic capsaicin pretreatment (125 mg/kg, s.c.). The inhibition of sympathetic transmission by guanethidine (30 mg/kg, s.c.) produced significant increase of the bladder reflex contractions activated by intravaginal capsaicin. Intravenous administration of the TRPV1 antagonist, capsazepine (3 mg/kg), significantly reduced the excitatory reflex response to capsaicin. Intravaginal administration of capsaicin (15 mug/50 mul), during distension-induced reflex bladder contractions, produced a transient block of reflexes, unaffected by guanethidine pretreatment. In conclusion, the stimulation of capsaicin-sensitive sensory nerve endings in the rat cervix-vagina induced a dual excitatory or inhibitory bladder response in anaesthetized female rats depending on the degree of bladder distension.     

The contribution of capsaicin-sensitive sensory nerves to xylene-induced visceral pain in conscious,freely moving rats

1. Intravesical instillation of xylene (10-100%, dissolved in silicone oil) through a catheter implanted into the bladder of conscious, freely-moving rats produced behavioural effects (licking of lower abdomen or perineal region) suggestive of intense visceral pain, not mimicked by topical application of the irritant on the urethral outlet. 2. The xylene-induced visceral pain was prevented, to the same extent, by systemic desensitization to capsaicin (50 mg/kg s.c.) performed in either adult or newborn rats, as well as by extrinsic bladder denervation (pelvic ganglionectomy), thus indicating the involvement of primary afferents in the bladder wall. 3. Other behavioural responses induced by xylene instillation into the bladder (hind limb hyperextension, grooming) were not affected by systemic capsaicin desensitization in either adult or newborn rats, but were abolished by bladder denervation. 4. Systemic capsaicin desensitization produced an almost complete depletion of substance P-, neurokinin A-like and calcitonin gene-related peptide-like immunoreactivity in the rat urinary bladder. 5. These findings indicate that, in addition to their role in activating reflex micturition, the neuropeptides-containing capsaicin-sensitive sensory nerves of the rat bladder are involved in chemogenic visceral pain.     

The effect of baclofen on the urinary bladder contraction accompanying micturition in anesthetized rats

We studied the effects of baclofen on the bladder contraction induced by infusion of Tyrode's solution into the urinary bladder in anesthetized rats. Baclofen (5 mg/kg, i.v.) completely inhibited bladder contraction and abolished the efferent discharges recorded from the left pelvic nerve, causing the bladder pressure to rise until solution leaked from the penis. The inhibitory effect of baclofen (5 mg/kg, i.v.) could not be reversed by picrotoxin (1 mg/kg, i.v., twice with an interval of 10 min) or naloxone (1 mg/kg, i.v.). In parallel with convulsion, strychnine (1 mg/kg, i.v.) contracted the bladder which had been inhibited by baclofen and generated electrical activities consisting of efferent discharges and electromyograms. The dose of intracerebroventricularly or intrathecally injected baclofen which completely inhibited the bladder contraction was 0.1 or 10 micrograms, respectively. After the inhibition of bladder contraction by i.v. injection of baclofen, electrical stimulation of the sacral cord could contract the bladder and cause a fall in bladder pressure to around the level existing after micturition. From these results, the active site of baclofen which is related to the inhibition of bladder contraction is thought to be the micturition center in the brain stem.     

Role of capsaicin-sensitive sensory nerves in mediation of the cardiovascular effects of the essential oil of croton zehntneri leaves in anaesthetized rats

The essential oil of Croton zehntneri Pax et Hoffm. (EOCZ) contains anethole (42%) and estragole (46%), two isomers that share some chemical structural similarities with capsaicin. The present study investigated the cardiovascular effects of EOCZ and the role of capsaicin-sensitive sensory nerve fibres in the mediation of these effects in anaesthetized rats. 2. Intravenous bolus injection of EOCZ (1-20 mg/kg) elicited dose-dependent hypotension and bradycardia that were immediate and transient. Similar responses were also observed with anethole and estragole (both at 10 mg/kg). After cervical bivagotomy or perineural treatment of both cervical vagus nerves with capsaicin (250 mg/mL) to selectively block the conduction of sensory C-fibres, both cardiovascular responses to EOCZ (10 mg/kg) were abolished. 3. Like capsaicin, an epigastric retrograde intra-arterial injection of EOCZ (10 mg/kg, i.a.) into the femoral artery elicited a monophasic hypotensive response. This reflex response was blocked by either neonatal pretreatment with capsaicin (50 mg/kg, s.c.) or intrathecal injection of the substance P receptor antagonist RP 67580 (7.8 nmol, at the spinal level L5-L6), suggesting that it is mediated exclusively by substance P-containing primary afferent fibres. 4. The cardiovascular responses to EOCZ (10 mg/kg, i.v.) were also significantly reduced by the selective vallinoid TPRV1 receptor antagonist capsazepine (1 mg/kg, i.v.). 5. It is concluded that i.v. administration of EOCZ in anaesthetized rats elicits a capsaicin-like bradycardic and depressor reflex, which appears to be mediated by the activation of vallinoid TPRV1 receptors located on vagal sensory nerves. Like capsaicin, i.a. injection of EOCZ induces a spinally mediated sensory reflex.     

Nociceptin protects capsaicin-sensitive afferent fibers in the rat urinary bladder from desensitization

Chemical stimulation of primary afferent nerves in the rat urinary bladder in vivo with topical capsaicin (1 microg in 50 microl saline) determines a dual motor response, consisting of a contractile effect mediated by tachykinins released from sensory nerves in the bladder wall and a transient activation of a bladder-to-bladder micturition reflex organized at the supraspinal level (chemoceptive micturition reflex). Both responses undergo complete desensitization upon repeated applications of capsaicin. The i.v. administration of the novel neuropeptide nociceptin (100 nmol/kg) produced a long-lasting protection from capsaicin desensitization of afferent nerves which mediate the chemoceptive micturition reflex. In fact a chemoceptive micturition reflex could be repeatedly evoked by topical capsaicin in nociceptin-pretreated rats. In sharp contrast, nociceptin did not influence the development of desensitization of the local response to capsaicin, corresponding to the 'efferent' function of capsaicin-sensitive afferent neurons. These results suggest that the afferent and 'efferent' function of capsaicin-sensitive primary afferent neurons (CSPANs) in the rat bladder are differentiated by nociceptin. Alternative mechanisms underlying this phenomenon are discussed.     

Effects of oxybutynin hydrochloride on the urinary bladder and urethra in in situ preparations

Effects of oxybutynin on the urinary bladder and urethra were studied in comparison with atropine and flavoxate in cats and rabbits. Oxybutynin at 10 mg/kg, i.v., significantly inhibited the bladder contractions induced by electrical stimulation of the peripheral end in pelvic nerve. Oxybutynin was about one half the potency of atropine. On the contrary, 10 mg/kg of flavoxate, i.v., showed both effects of potentiation and inhibition. The bladder contractions induced by acetylcholine (ACh) and AHR-602 were markedly inhibited by oxybutynin and atropine. Oxybutynin was about one-fifteenth the potency of atropine. DMPP-induced contractions were inhibited by oxybutynin and atropine in a high dose, but oxybutynin was about two-fifths the potency of atropine. In addition, 3 mg/kg of oxybutynin, i.v., inhibited the contraction induced by hypogastric nerve stimulation, but 10 mg/kg of oxybutynin, i.v., significantly inhibited this contraction following initial potentiation. Oxybutynin showed an inhibitory effect on spontaneous rhythmical contraction, bladder tone and pelvic nerve discharge, similar to the effects of atropine. On the contrary, flavoxate potentiated this contraction and increased the bladder tone and pelvic and hypogastric nerve discharge. Urethra contractions induced by norepinephrine, ACh and hypogastric nerve stimulation were inhibited by oxybutynin, but not markedly. Oxybutynin and atropine dose-dependently increased the infusion volume, bladder volume capacity and micturition threshold pressure in the cystometrogram in rabbits. Flavoxate also increased them. From these results, it si suggested that oxybutynin is therapeutically a useful agent for pollakisurea nervosa.     

Effects of 3-methyl-4-oxo-2-phenyl-N-[2-piperidinyl) ethyl]-4H-1-benzopyran-8-carboxyamide hydrochloride monohydrate (FL-155), a new anti-pollakiuria agent, on rhythmic bladder contractions in anesthetized rats

The effects of FL-155, which was synthesized to develop a new orally-active anti-pollakiuria agent, on the rhythmic bladder contractions were studied in anesthetized rats. At a pressure exceeding 10 cm H2O in the bladder, a rhythmic bladder contraction was observed up to at least 120 min. This response was abolished by a spinal (C1 level) cut, cuts of both pelvic nerves, thiopental (3.0 mg/kg, i.v.) or lidocaine (1.0 mg/kg, i.v.); and atropine (0.01 mg/kg, i.v.) strongly inhibited the amplitude of the response. FL-155 and flavoxate, in intravenous (0.3-3.0 mg/kg and 1.0-3.0 mg/kg, respectively) and intraduodenal (12.5-100 mg/kg and 200-400 mg/kg, respectively) administrations, dose-dependently abolished the rhythmic bladder contractions, and FL-155 was 8-16 times more potent than flavoxate in intraduodenal administrations. These results suggest that the rhythmic bladder contraction in anesthetized rat may be a polysynaptic reflex through pelvic nerves and the central nervous system (supraspinal level), and FL-155 appears to be a candidate for an orally active anti-pollakiuria agent.     

In vivo inhibitory effects of stimulation at the central end of the pelvic nerve severed from urinary bladder on urinary bladder contraction in rats

Two- or five-Hz electrical stimulation of the central end of the left pelvic nerve severed from the urinary bladder in rats inhibited bladder contraction induced by intravesical infusion of Tyrode's solution. Inhibition of bladder motility by 2-Hz nerve stimulation appeared after pretreatment with strychnine (0.3 mg/kg, i.v.), naloxone (1 mg/kg, i.v.) and picrotoxin (1 mg/kg, i.v.). Hypogastric nerve stimulation, however, did not affect bladder contraction. These results suggest the presence of an inhibitory mechanism on the pelvic motoneuron activated by contralateral pelvic nerve stimulation in rats.     

Effects of tiropramide hydrochloride on the isolated detrusor and intravesical pressure of the bladder in situ in rats]

The effects of tiropramide on the isolated detrusor and intravesical pressure of the bladder in situ in rats were compared with those of flavoxate, oxybutynin and terodiline. The IC50 values (x 10(-5) M) of tiropramide for carbachol (CCh)-, K+ (60 mM)-, Ba2+ (10 mM)-, and electrical stimulation-induced contractions were 3.6, 4.2, 5.8, and 2.9, respectively. The four antispasmodics used (2 and 4 mg/kg, i.v., each) abolished the rhythmic bladder contractions in situ in anesthesized rats. Of the four compounds, oxybutynin was most potent and no significant differences were observed between the inhibitory effects of tiropramide, flavoxate and terodiline. The administration of flavoxate (30 and 60 mg/kg) into the duodenum little influenced the rhythmic bladder contractions. Tiropramide, flavoxate, oxybutynin and terodiline (8 and 12 mg/kg, i.v., each) dose-dependently prolonged the time to the volume-evoked micturition reflex, and the activity of tiropramide was not statistically different from those of the other three antispasmodics. Under unilateral pelvic and bilateral hypogastric nerve transection, both of the contractions induced by electrical stimulation of the peripheral and central cut ends of the pelvic nerve were dose-dependently inhibited to the same extent by tiropramide and terodiline. These results suggest that the effects of tiropramide on the function of urinary bladder in rats may be mainly due to direct actions on the smooth muscle, and that tiropramide is more potent than flavoxate and less potent than oxybutynin and terodiline.     

Inhibitory effect of inaperisone hydrochloride (inaperisone), a new centrally acting muscle relaxant, on the micturition reflex.

We examined the effects of inaperisone hydrochloride (inaperisone), a new centrally acting muscle relaxant, on bladder function in anesthetized rats and isolated rat tissues. We also investigated its mechanism of action. When a balloon inserted into the bladder was expanded, rhythmic bladder contractions were observed; inaperisone (4 mg/kg i.v.) abolished these contractions, in both normal and decerebrated rats. The bladder tonus or bladder contraction induced by peripheral stimulation of the pelvic nerve was barely inhibited by inaperisone (4 mg/kg i.v.), but this dose of inaperisone abolished the efferent discharge from the pelvic nerve that accompanied the rhythmic bladder contractions. The doses of intracerebroventricularly (i.c.v.) and intrathecally injected inaperisone which abolished the rhythmic bladder contractions were 10 and 100 micrograms, respectively. The inhibitory effects of inaperisone (4 mg/kg i.v.) were not diminished by naloxone (1 mg/kg i.v.) or by bicuculline (0.5 mg/kg i.v.), but were diminished by phaclofen (30 mg/kg i.v. or 300 micrograms i.c.v.). The specific binding of [3H]baclofen to rat brain synaptosomal membranes was barely inhibited by inaperisone (up to 1 mM). From these results, it is speculated that, among other possible mechanisms, inaperisone inhibits the micturition reflex by acting indirectly on GABAB receptors in the brainstem.     

Vesico-inhibitory responses and capsaicin-sensitive afferents in rats

Summary (1) The effect of perineal pinching and distension of a balloon inserted into the colon on motility of the urinary bladder has been investigated in adult urethane-anesthetized rats pretreated with capsaicin (50 mg/kg s.c.) or its vehicle 4 days before the experiments. (2) At bladder volumes which were sufficient to elicit reflex micturition, perineal pinching or colonic distension transiently inhibited the ongoing bladder voiding contraction. The somato-vesical inhibitory response was markedly reduced or even abolished by division of pudendal nerves. Neither the somato-vesical nor the colovesical inhibitory response were modified by desensitization with systemically administered capsaicin. (3) Intraurethral administration of capsaicin produced a transient inhibition of the reflexly-activated bladder contractions. A second administration of the drug was less effective, indicating desensitization. Intravenously administered capsaicin had a similar inhibitory effect on bladder motility. (4) The vesico-inhibitory response produced by intraurethral administration of capsaicin was not affected by phentolamine, propranolol, guanethidine, picrotoxin or naloxone, while it was greatly reduced or even abolished by bilateral section of the pudendal nerves. (5) These findings provide evidence that capsaicin-sensitive chemoreceptors in the rat urethra are involved in generating a vesico-inhibitory response via pudendal nerves. On the other hand, no evidence was found for the participation of capsaicin-sensitive nerves in the generation of the somato- or colo-vesical inhibitory response. Send offprint requests to C. A. Maggi at the above address     

Mode of inhibitory action of propiverine hydrochloride on the micturition movements of the bladder in dogs

Propiverine hydrochloride (P-4) is a new derivative of benzilic acid. The effect of P-4 on the vesico-detrusor reflex (corresponding to the first reflex of Barrington) in anesthetized or decerebrated dogs was studied to elucidate the mode of action of the drug. When bladder contraction was induced by electrical stimulation of the distal ending of the pelvic nerve under the bilateral pelvic nerve and hypogastric nerve transection, P-4 (2, 5 and 10 mg/kg, i.v.) significantly inhibited the contraction. A similar effect was also observed following intravenous administration of flavoxate (10 and 20 mg/kg), verapamil (1 mg/kg) or propantheline (2 mg/kg), while thiopental (4 mg/kg, i.v.) had no significant effect. When the bladder was filled under the bilateral pelvic nerve and hypogastric nerve transection, an increase of afferent impulses from the distal ending of a pelvic vesical branch was observed. P-4 (10 mg/kg, i.v.) had no effect on the afferent impulses. When the central endings of the pelvic vesical branches were electrically stimulated, reflex discharges were noted from a pelvic vesical branch on the contralateral side. Thiopental (2 and 4 mg/kg, i.v.) markedly decreased the reflex discharge, whereas P-4 (10 mg/kg, i.v.) caused no such inhibition. These findings suggest that the inhibition of the vesico-detrusor reflex by P-4 may result from its inhibitory action on the efferent terminal of the pelvic nerve.     

Evidence for the involvement of bradykinin in chemically-evoked cystitis in anaesthetized rats

Summary The effect of Hoe 140, a potent bradykinin B2 receptor antagonist, on the micturition reflex and detrusor hyperreflexia induced by chemical cystitis has been investigated in anaesthetized rats. Hoe 140 (1–100 nmol/kg i. v.) produced a dose-dependent blockade of the contraction of the rat urinary bladder induced by i. v. administration of bradykinin (100 nmol/kg) without affecting the response produced by the selective tachykinin NK-1 receptor agonist, [Sar⁹] substance P (SP) sulfone (1 nmol/kg i. v.). At doses which produce selective and long-lasting blockade of bradykinin receptors in the urinary bladder, Hoe 140 did not modify urodynamic parameters in normal rats.Intravesical instillation of xylene in female rats decreased bladder capacity and increased micturition frequency. These effects also occurred in rats pretreated with capsaicin as adults. Hoe 140 did not modify xylene-induced cystitis. Intraperitoneal administration of cyclophosphamide (150 mg/kg, 48 h before) decreased bladder capacity and increased micturition frequency. These effects of cyclophosphamide were abolished in rats pretreated with capsaicin as adults. Hoe 140 increased bladder capacity and decreased micturition frequency in rats pretreated with cyclophosphamide.Addition of bradykinin (10 µmol/l) to the medium in the superfused rat urinary bladder preparation evoked a prompt increase in the outflow of calcitonin gene-related peptide like immunoreactivity (CGRP-LI). Hoe 140 (3 µmol/l) inhibited (by about 50%) the CGRP-LI outflow stimulated by bradykinin.These findings demonstrate the participation of bradykinin, through 132 receptors, in the genesis of detrusor hyperreflexia during cyclophosphamide-induced cystitis. Capsaicin-sensitive primary afferent neurons are a likely target for Hoe 140 action in this model of experimental cystitis, as exemplified by its ability to prevent CGRP-LI outflow by bradykinin.Correspondence to C. A. Maggi at the above address     

Effects of (+/-)-4'-ethyl-2-methyl-3-(l-pyrrolidinyl) propiophenone hydrochloride (HY-770) on the bladder function

The effects of HY-770 on micturition reflexes in rats, dogs and cats and urethral pressure in dogs were compared with those of flavoxate.HC1 (flavoxate), terodiline.HCl (terodiline) and oxybutynin.HCl (oxybutynin). 1) HY-770, in intravenous (2 and 4 mg/kg) and intraduodenal (12.5 and 25 mg/kg) administrations, dose-dependently abolished the rhythmic bladder contractions in anesthetized rats. The activity of HY-770, in intravenous administration (i.v.), was almost equal to those of flavoxate, terodiline and oxybutynin; and the activity of HY-770, like terodiline, was more potent than that of flavoxate in intraduodenal administration (i.d.). 2) In the cystometrograms, HY-770 (3, 4 or 8 mg/kg, i.v.) dose-dependently increased the time to micturition (capacity of bladder) without decreasing the amplitude of micturition contraction in anesthetized rats, dogs and cats, and HY-770 (25 mg/kg, i.d.) also increased the capacity in anesthetized cats. 3) HY-770 (4 and 8 mg/kg, i.v.) dose-dependently increased the capacity of the bladder in the cystometrograms of pollakiuria induced by either transection of both the hypogastric nerves or chronic cannulation to the bladder in anesthetized or conscious rats, respectively. 4) HY-770 (25 mg/kg, i.d.) slightly decreased the urethral pressure in anesthetized dogs. These results suggest that HY-770 is a promising drug for the treatment of pollakiuria induced by a neurogenic bladder or unstable bladder, etc.     

Aminophylline differentiates between the depressant effects of morphine on the spinal nociceptive reflex and on the spinal ascending activity evoked from afferent C fibres

The action of aminophylline on anti-nociceptive effects of morphine in rats was tested on the tail-flick response to noxious heat and on the activity evoked in ascending axons of the spinal cord by stimulation of nociceptive afferents. The depression of the tail-flick response produced by an intraperitoneal (i.p.) injection of morphine 2 mg/kg in intact and spinal rats was abolished by an i.p. injection of aminophylline 25 mg/kg. The activity evoked in ascending axons of spinal rats by electrical stimulation of afferent C fibres of the sural nerve was depressed by an intravenous (i.v.) injection of morphine 2 mg/kg. Aminophylline 25 mg/kg injected i.v. after morphine produced a slight and transient increase in the ascending activity immediately after its administration but did not abolish the depressant effect of morphine. Naloxone 0.2 mg/kg administered after aminophylline antagonized the depressant effect of morphine on the ascending activity. It is suggested that morphine exerts its depressant effect on the two nociceptive responses (the motor and the sensory response) by different mechanisms, one being sensitive to aminophylline, the other being relatively resistant to the action of the purine derivative.     

MEN 11,420, a peptide tachykinin NK2 receptor antagonist, reduces motor responses induced by the intravesical administration of capsaicin in vivo

This study investigates the role of tachykinin NK₁ and NK₂ receptors in motor responses induced by the intravesical instillation of capsaicin in urethane-anaesthetized rats. SR 140,333 (1 μmol/kg, i.v.), a non-peptide NK₁ receptor antagonist, abolished urinary bladder contractions induced by the selective NK₁ receptor agonist [Sar⁹]SP-sulfone (0.1-100 nmol/kg, i.v.) without affecting those induced by the NK₂ receptor agonist [?Ala⁸]NKA(4-10). MEN 11,420 (100 nmol/kg, i.v.), a cyclic peptide NK₂ receptor antagonist, abolished bladder contractions induced by [?Ala⁸]NKA(4-10) (0.3-300 nmol/kg, i.v.) without modifying those induced by [Sar⁹]SP-sulfone. Intravesical instillation of capsaicin (6 nmol/0.6 ml/rat) produced a motor response consisting in a primary contraction followed by a series of high amplitude phasic contractions. The intravesical instillation of saline (0.6 ml/rat) produced a primary contraction of lower amplitude with respect to that induced by capsaicin and the total area under the curve was also lower in saline-instilled rats, however the number and the amplitude of phasic contractions was similar to that induced by capsaicin. MEN 11,420 (100 nmol/kg, i.v.) did not modify motor responses induced by the intravesical administration of saline. In contrast, in capsaicin-instilled rats, MEN 11,420 (100 nmol/kg, i.v.) reduced the primary contraction, the area under the curve and also the number of phasic contractions. SR 140,333 (1 μmol/kg, i.v.) reduced the primary contraction but not other parameters. The combination of SR 140,333 (1 μmol/kg, i.v.) and MEN 11,420 (100 nmol/kg, i.v.) produced an additive inhibitory effect on the primary contraction but not a further inhibition on other parameters with respect to that observed with MEN 11,420 alone. In hexamethonium (110 μmol/kg, i.v.)-pretreated animals the intravesical instillation of capsaicin produced a tonic contraction having greater amplitude and area than that induced by saline. MEN 11,420, but not SR 140,333, significantly reduced the bladder response to capsaicin in hexamethonium-pretreated rats. Again, the combined administration of MEN 11,420 and SR 140,333 did not produce further inhibitory effect in comparison to MEN 11,420 alone. It is concluded that the motor responses induced by the intravesical instillation of capsaicin are mediated by the activation of peripheral tachykinin NK₂ receptors. Received: 11 February 1997 / Accepted: 17 April 1997