Biomedical subjects

Y Ukai

Publications and source records attributed to Y Ukai.

At least 19 recordsLinked to original sources

PubMed2004

Quantitative trait loci for phyllochron and tillering in rice.

Morphogenetic processes in sequentially growing leaves and tiller buds are highly synchronized in rice ( Oryza sativa L.). Consequently, the appearance of successive leaves in the main tiller acts as the "pacemaker" for the whole shoot system development. The time interval between the appearance of successive leaves (days/leaf) in the main tiller is called the 'phyllochron'. The objectives of the investigation reported here were: (1) to identify quantitative trait loci (QTLs) that control rice phyllochron and (2) to understand the roles of phyllochron QTLs as an underlying developmental factor for rice tillering. For this purpose we developed a set of recombinant inbred lines derived from a cross between IR36 ( indica) and Genjah Wangkal (tropical japonica). Composite interval mapping detected three phyllochron QTLs located on chromosomes 4, 10 and 11, where the presence of a Genjah Wangkal allele increased phyllochron. The largest QTL (on chromosome 4) was located on the genomic region syntenic to the vicinity of the maize Teopod 2 mutation, while the QTL on chromosome 10 was close to the rice plastochron 1 mutation. These three phyllochron QTLs failed to coincide with major tiller number QTLs. However, one tiller number QTL was associated with small LOD peaks for phyllochron and tiller-bud dormancy that were linked in coupling phase, suggesting that linked small effects of phyllochron and tiller-bud dormancy might result in a multiplicative effect on tiller number.

Chromosome Mapping↗

PubMed2004

Inheritance of early elongation ability in floating rice revealed by diallel and QTL analyses.

In floating rice, stem elongation begins much earlier than in non-floating rice, which is the major survival mechanism for flooding. Inheritance of this early elongation ability was studied using diallel and quantitative trait locus (QTL) analyses. The diallel analysis was undertaken using a set of 6x6 half-diallel crosses involving four floating ("Goai", "Habiganj Aman VIII", "Badal 106", and Oryza rufipogon strain W120) and two non-floating ("Latisail" and "Patnai 23") parents. The additive gene effects were higher than the dominant effects. The dominant alleles were concentrated in the cultivated floating parents (("Goai", "Habiganj Aman VIII", "Badal 106"), whereas the recessive alleles were in the wild floating parent (W120). A QTL analysis using a "Patnai 23" x "Goai" F(2) population detected two putative QTLs. Of these QTLs, the one on chromosome 12 behaved as a partially dominant major gene that explained more than half of the total genetic variation.

Alleles↗

PubMed2003

A novel pyrrole derivative, NS-8, suppresses the rat micturition reflex by inhibiting afferent pelvic nerve activity.

OBJECTIVE: To investigate the suppressive effect of a newly synthesized compound, 2-amino-3-cyano-5-(2-fluorophenyl)-4-methylpyrrole (NS-8), on micturition, and its mode and sites of action in rats. MATERIALS AND METHODS: Female rats were anaesthetized with urethane, and isovolumetric bladder contractions and cystometrograms recorded. The pelvic afferent discharges from the bladder were also monitored. RESULTS: In the cystometric study, NS-8 increased the bladder capacity without affecting the maximum bladder contraction pressure, an effect unlike that of currently used anticholinergic drugs for the overactive bladder, which commonly decrease the maximum bladder contraction pressure. Intravesical and intravenous injection of NS-8 inhibited isovolumetric bladder contractions in a dose-dependent manner without affecting their amplitude, whereas intracerebroventricular injection with NS-8 had no such effect. During the urine storage phase of the cystometrogram, NS-8 decreased the discharge rate of the afferent pelvic nerve from the bladder, in association with a decrease in the increase in intravesical pressure. CONCLUSION: NS-8 suppressed the micturition reflex by decreasing afferent pelvic nerve activity. Activation of calcium-sensitive potassium channel of the bladder may be responsible for such an effect. This agent has the potential to treat patients with urinary frequency and incontinence.

Animals↗

PubMed2002

A new enzymic method for the isolation and culture of human bladder body smooth muscle cells.

Cultured cells of the human urinary bladder smooth muscle are useful for investigating bladder function, but methods for culturing them are not well developed. We have now established a novel enzymic technique. The smooth muscle layer was separated out and incubated with 0.2% trypsin for 30 min at 37 degrees C. The samples were then minced and incubated with 0.1% collagenase for 30 min and centrifuged at 900 g. The pellets were resuspended in RPMI-1640 medium containing 10% fetal calf serum (FCS) and centrifuged at 250 g. The smooth muscle cells from the supernatant were cultured in RPMI-1640 containing 10% FCS. The cells grew to confluence after 7-10 days, forming the "hills and valleys" growth pattern characteristic of smooth muscle cells. Immunostaining with anti-alpha-actin, anti-myosin, and anti-caldesmon antibodies demonstrated that 99% of the cells were smooth muscle cells. To investigate the pharmacological properties of the cultured cells, we determined the inhibitory effect of muscarinic receptor antagonists on the binding of [3H]N-methylscopolamine to membranes from cultured cells. The pKi values obtained for six antagonists agreed with the corresponding values for transfected cells expressing the human muscarinic M2 subtype. Furthermore, carbachol produced an increase in the concentration of cytoplasmic free Ca2+ an action that was blocked by 4-diphenylacetoxy-N-methylpiperidine methiodide, an M3 selective antagonist. This result suggests that these cells express functional M3 muscarinic receptors, in addition to M2 receptors. The subcultured cells therefore appear to be unaffected by our new isolation method.

Calcium↗

PubMed2001

Antibody fusions with fluorescent proteins: a versatile reagent for profiling protein expression.

We developed a system by which antibodies, fused to fluorescent proteins with different wavelengths, can be prepared within a month against various antigens. An antibody library composed of a large number of single-chain Fv-CL fragment was constructed by means of a phage-display system. The constructs were designed to facilitate changing of the protein forms by simple enzyme manipulation. In the present study, we adopted a molecular form of antibody in which a single-chain Fv-CL fragment is fused with a green fluorescent protein (GFP) or red fluorescent protein (RFP). In addition, a His-tag was inserted between CL and GFP (or RFP). We describe the utility of this system using Caenorhabditis elegans embryo as a model.

Amino Acid Sequence↗

PubMed2001

Reversal by NS-7, a neuroprotective compound, of the decrease in transcription factor CREB mRNA expression in rat brain after permanent middle cerebral artery occlusion.

The effect of a neuroprotective agent NS-7 on changes in mRNA expressions for cyclic AMP responsive element binding protein (CREB) and several neurotrophins was examined in the rat cerebral cortex after permanent middle cerebral artery occlusion (MCAO). Significant reduction in mRNA expressions for CREB was observed at 24h after MCAO. NS-7 (0.5mg/kg), when injected at 6h after MCAO, significantly reversed the decreased expression for CREB mRNA. In addition, the mRNA expression for basic fibroblast growth factor (bFGF) was also significantly enhanced by NS-7 in MCA-occluded but not in sham-operated rats. On the other hand, the mRNAs for interluekin-6 and inducible-type nitric oxide synthase were markedly induced in the cerebral cortex of MCA-occluded rats, which was not significantly reversed by NS-7. Therefore, it is suggested that the reversal of decrease in CREB mRNA and concomitant increase in mRNA expression for bFGF may contribute to the neuroprotective action of NS-7.

Animals↗

PubMed2001

Cerebroprotective action of a Na+/Ca2+ channel blocker NS-7. I. Effect on the cerebral infarction and edema at the acute stage of permanent middle cerebral artery occlusion in rats.

The effect of a novel Na+/Ca2+ channel blocker NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride] on the cerebral infarction, edema and brain energy metabolism was investigated in rats after permanent middle cerebral artery occlusion (MCAO). The infarction and brain water content were evaluated at 48 h and 24 h after MCAO, respectively. A single bolus injection of NS-7 (0.03125-0.25 mg/kg) immediately after MCAO produced a dose-dependent reduction in the infarct volume as well as edema both in the cerebral cortex and striatum. Glycerol (4 g/kg) also decreased water content both in the occluded and non-occluded brain, but it did not reduce the size of cerebral infarction. Unlike glycerol, NS-7 did not change the water content in non-occluded brain. Moreover, a significant protective action was still observed even when NS-7 was injected once at 12 h after occlusion. In addition, NS-7 significantly reversed the decrease in tissue ATP content observed at 3 h but not at 0.5 h after MCAO. These findings suggest that a Na+/Ca2+ channel blocker NS-7 protects cerebral tissues against ischemic insults by improving the disturbance of cerebral energy metabolism and suppressing the cerebral edema.

Adenosine Diphosphate↗

PubMed2001

Cerebroprotective action of a Na+/Ca2+ channel blocker NS-7. II. Effect on the cerebral infarction, behavioral and cognitive impairments at the chronic stage of permanent middle cerebral artery occlusion in rats.

We have previously shown that NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride] reduces the size of cerebral infarction measured by 2,3,5-triphenyltetrazolium chloride staining at 48 h after permanent middle cerebral artery occlusion (MCAO) in rats. To determine whether NS-7 improves the pathological and behavioral changes at the chronic stage of MCAO, the effect of this compound on the cerebral infarction as well as the neurological and cognitive impairments was investigated 7 days after MCAO. Single or five daily injections of NS-7 (0.125-0.5 mg/kg, i.v.) significantly reduced the infarct volume and improved the neuronal dysfunction including the hind leg paralysis, walking disability and motor incoordination, and the deficit of passive avoidance task, although the neuroprotective efficacy was not different among these dosing regimens. On the other hand, the effects of single versus repeated injections of NS-7 at 0.1 or 0.2 mg/kg on the neurological symptoms were compared at 4 weeks after MCAO. At a lower dose, repeated but not single injection of NS-7 significantly improved the neurological symptoms, although the single injection was effective at a higher dose. From these findings, it is suggested that NS-7 reverses the behavioral and cognitive dysfunction observed at the chronic stage of cerebral ischemia by suppressing the cerebral infarction.

Animals↗

PubMed2001

Release of endothelial nitric oxide in coronary arteries by celiprolol, a beta(1)-adrenoceptor antagonist: possible clinical relevance.

Mechanisms underlying celiprolol-induced vasodilatation were analyzed in isolated porcine coronary arteries. Celiprolol induced dose-related relaxation of the artery rings with endothelium, an effect which was suppressed by N(G)-nitro-L-arginine methylester (L-NAME), nitric oxide (NO) scavenger, guanylate cyclase inhibitor, endothelium denudation, and removal of Ca(2+). L-NAME contracted, and superoxide dismutase relaxed, the arteries only when the endothelium was preserved. Neither superoxide dismutase nor beta-adrenoceptor antagonists changed celiprolol-induced relaxations. Celiprolol increased the cyclic GMP content in the tissue. The release of NO from endothelium, estimated by the extracellular production of cyclic GMP in arteries incubated in medium containing guanylate cyclase and GTP, was augmented by celiprolol, and L-NAME abolished this action of celiprolol. It is concluded that celiprolol elicits relaxation by acting on sites other than beta-adrenoceptors in the endothelium and by releasing NO, which activates soluble guanylate cyclase in smooth muscle and produces cyclic GMP. Scavenging of superoxide anions from the endothelium does not seem to account for the induced relaxation.

Adrenergic beta-1 Receptor Antagonists↗

PubMed2001

Detection of closely linked multiple quantitative trait loci using a genetic algorithm.

The existence of a quantitative trait locus (QTL) is usually tested using the likelihood of the quantitative trait on the basis of phenotypic character data plus the recombination fraction between QTL and flanking markers. When doing this, the likelihood is calculated for all possible locations on the linkage map. When multiple QTL are suspected close by, it is impractical to calculate the likelihood for all possible combinations of numbers and locations of QTL. Here, we propose a genetic algorithm (GA) for the heuristic solution of this problem. GA can globally search the optimum by improving the "genotype" with alterations called "recombination" and "mutation." The "genotype" of our GA is the number and location of QTL. The "fitness" is a function based on the likelihood plus Akaike's information criterion (AIC), which helps avoid false-positive QTL. A simulation study comparing the new method with existing QTL mapping packages shows the advantage of the new GA. The GA reliably distinguishes multiple QTL located in a single marker interval.

Algorithms↗

PubMed2001

Effective plasma concentration of a novel Na+/Ca2+ channel blocker NS-7 for its cerebroprotective actions in rats with a transient middle cerebral artery occlusion.

The effect of a novel Na+/Ca2+ channel blocker NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride] on the cerebral infarction, edema, and mortality was examined in rats with a transient middle cerebral artery occlusion (MCAO), and the effective plasma concentration of this compound for producing the cerebroprotective action was subsequently determined. MCA was occluded by inserting a thread through internal carotid artery for 2 h, and then recirculated for 6 h. NS-7 (0.125-1 mg/kg), when injected i.v. immediately after recirculation, significantly reduced the infarct volume as well as the cerebral edema. Delayed treatment with NS-7 at 1 h after recirculation produced an equivalent inhibition of the infarction, and was still effective, although to a lesser extent, when injected at 2 h but not 3 h after recirculation. Glycerol (4 g/kg) suppressed the cerebral edema but did not reduce the size of cerebral infarction in the cerebral cortex or striatum. Therefore, it is likely that the suppression of brain edema does not always lead to the reduction of the infarct size. NS-7 treated in combination with glycerol further decreased the water content in the occluded brain. Moreover, NS-7 significantly lowered the mortality observed up to 10 days after a transient MCAO. From these data, it is suggested that the presence of NS-7 in plasma during 1 to 3 h after recirculation is important for producing the neuroprotective action. To determine the pharmacologically effective plasma concentration of NS-7, the effect of continuous infusion of this compound on the cerebral infarction was examined. Infusion of NS-7 at 0.3 mg/kg over 2 h, starting immediately after recirculation, significantly reduced the infarct size. Its plasma concentration during 1 to 3 h was 14.5 to 28.5 ng/ml (36.9-72.3 nM). From these finding it is suggested that NS-7 has a potent anti-infarct action in addition to antiedema action in the rat transient MCAO model. Moreover, its effective plasma concentration was assumed to be 36.9 to 72.3 nM.

Animals↗

PubMed2000

Determination and bioimaging method for nitric oxide in biological specimens by diaminofluorescein fluorometry.

A simple and sensitive assay and a cellular bioimaging method for nitric oxide (NO) were developed using a novel diaminofluorescein DAF-FM and its diacetate. DAF-FM is converted via an NO-specific mechanism to an intensely fluorescent triazole derivative. For the measurement of NO, the triazole derivative of DAF-FM was determined by reversed-phase high-performance liquid chromatography with fluorescence detection. In the presence of 1 microM DAF-FM, the concentrations of NOR-1, an NO donor, in the range of 2-200 nM were linearly related to the fluorescence intensity. This sensitive NO assay enabled us to detect the spontaneous and substance P-induced NO release from isolated porcine coronary arteries, both of which were dependent entirely on the NO synthase activity in vascular endothelial cells. We also obtained fluorescence images of cultured smooth muscle cells of the rat urinary bladder after loading with DAF-FM diacetate. In the cells pretreated with cytokines, the fluorescence intensity increased with time after DAF-FM loading. This increase in the fluorescence intensity was blocked by prior treatment of the muscle cells with an NO synthase inhibitor, N(G)-nitro-l-arginine methyl ester. Therefore, the present novel diaminofluorescein fluorometry should be useful not only for sensitive NO assay, but also for NO imaging in a variety of biological specimens.

Animals↗

PubMed2000

Involvement of Na+ and Ca2+ channel activation and resultant nitric oxide synthesis in glutamate-mediated hypoxic injury in rat cerebrocortical slices.

The role of Na+ and Ca2+ channels in glutamate-mediated hypoxic injury was investigated in slices of the rat cerebral cortex. Hypoxic injury was determined by mitochondrial reduction of 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyltetrazolium bromide after exposure of brain slices to 30-min of hypoxia/glucose deprivation followed by 3-h of reoxygenation. Endogenous glutamate release was markedly elevated during hypoxia/glucose deprivation, but it returned almost to basal level during reoxygenation. Hypoxic injury was prevented by MK-801 or 6-cyano-7-nitroquinoxaline-2,3-dione. Combined treatment with omega-conotoxin GVIA, omega-agatoxin IVA, and tetrodotoxin reversed the hypoxic injury, although none of these agents alone or nifedipine was effective. Moreover, a novel Na+/Ca2+ channel blocker NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride] significantly inhibited the hypoxic injury. Several inhibitors of nitric oxide synthase also blocked the hypoxic injury. Consistently, nitric oxide synthesis, as estimated from cyclic GMP formation in the extracellular fluids, was enhanced during hypoxia/glucose deprivation. NS-7 and other Na+ and Ca2+ channel blockers suppressed the enhancement of nitric oxide synthesis, although these compounds alone, or in combination, did not reduce hypoxic glutamate release. These findings suggest that hypoxic injury in rat cerebrocortical slices is triggered by glutamate and subsequent enhancement of nitric oxide synthesis through activation of both Na+ and Ca2+ channels. Thus, the simultaneous blockade of both Na+ channel as well as N-type and P/Q-type Ca2+ channels is required to sufficiently reverse the hypoxic injury.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2000

Involvement of peroxynitrite and hydroxyradical generated from nitric oxide in hypoxia/reoxygenation injury in rat cerebrocortical slices.

The changes in nitric oxide (NO) formation during hypoxia and reoxygenation were measured in slices of rat cerebral cortex, and the possible involvement of NO and its decomposition products, including peroxynitrite and hydroxyradical, in the hypoxia/reoxygenation injury was subsequently investigated. NO formation estimated from cGMP accumulation in the extracellular fluids was enhanced during hypoxia and to a lesser extent in the reoxygenation period. The mRNA for inducible NO synthase (NOS) was detected 3-5 h after reoxygenation, although neuronal NOS mRNA decreased after reoxygenation. Several NOS inhibitors such as N(G)-monomethyl-L-arginine and N(G)-nitro-L-arginine blocked not only the NO formation but also the hypoxia/reoxygenation injury as determined by lactate dehydrogenase (LDH) leakage. The hypoxia/reoxygenation injury was prevented by peroxynitrite scavengers including deferoxamine and uric acid, or several hydroxyradical scavengers such as dimethylthiourea, 2-mercaptopropionylglycine and D(-) mannitol. In addition, the hypoxia/reoxygenation injury was attenuated by poly(ADP-ribose)synthetase inhibitors such as banzamide, 3-aminobenzamide and 1,5-isoquinolinediol. On the other hand, both N-morpholinosidnonimine, a peroxynitrite generator, and hydroxyradical-liberating solution containing FeCl(3)-ADP and dihydroxyfumarate caused a marked LDH leakage in normoxic slices. These findings suggest that the enhanced formation of NO causes hypoxia/reoxygenation injury after degradation to peroxynitrite and hydroxyradical and the resultant activation of poly(ADP-ribose)synthetase.

Adenosine Triphosphate↗

PubMed2000

Role of metabotropic glutamate receptor subclasses in modulation of adenylyl cyclase activity by a nootropic NS-105.

The involvement of metabotropic glutamate (mGlu) receptors in the modulatory actions of a novel cognition enhancer, (+)-5-oxo-D-prolinepiperidinamide monohydrate (NS-105), on adenylyl cyclase activity in rat cerebrocortical membranes and primary neuronal cultures was investigated using selective antagonists and antisense oligodeoxynucleotides for mGlu receptor subclasses. In rat cerebrocortical membranes, the inhibitory action of NS-105 (0.1 microM) on forskolin-stimulated cAMP formation was blocked by a group II mGlu receptor antagonist, (+/-)-alpha-ethylglutamic acid, and by a group III antagonist, (+)-2-amino-2-methyl-4-phosphonobutanoic acid (MAP-4), but not by a group I antagonist, (+/-)-1-aminoindan-1,5-dicarboxylic acid (AIDA), whereas the facilitation of cAMP formation by NS-105 (1 microM) in pertussis toxin-pretreated membranes was abolished by AIDA but not by (+/-)-alpha-ethylglutamic acid or MAP-4. In primary cultured neurons of mouse cerebral cortex, the inhibitory action of NS-105 on adenylyl cyclase activity disappeared after treatment with antisense oligodeoxynucleotides for group II (mGlu(2) and mGlu(3) receptors) and group III (mGlu(4) and mGlu(7) receptors) but not group I (mGlu(5) receptor) mGlu receptor subclasses. These findings suggest that the inhibitory action of NS-105 on adenylyl cyclase activity is mediated through group II and group III mGlu receptor subclasses while the facilitatory action is dependent on the group I mGlu receptor subclass.

Adenylyl Cyclases↗

PubMed2000

Preferential inhibition by a novel Na(+)/Ca(2+) channel blocker NS-7 of severe to mild hypoxic injury in rat cerebrocortical slices: A possible involvement of a highly voltage-dependent blockade of Ca(2+) channel.

The hypoxic injury was induced in rat cerebrocortical slices by the exposure to hypoxia for 45 min in the absence or presence of 3 mM glucose, followed by reoxygenation for 5 h. The injury was more pronounced in the absence of glucose (severe hypoxic injury) than in the presence of glucose (mild hypoxic injury). A novel Na(+)/Ca(2+) channel blocker, NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride], at 3 to 30 microM inhibited preferentially the severe hypoxic injury, whereas MK-801, omega-conotoxin GVIA (omega-CTX), and N(G)-nitro-L-arginine methylester suppressed preferentially the mild hypoxic injury. The extracellular cyclic GMP formation, a marker of nitric oxide synthesis, was enhanced during hypoxia, although the extent was greater in the absence of glucose. As observed in the hypoxic injury, NS-7 preferentially inhibited the cyclic GMP formation induced by severe hypoxic insults, whereas MK-801 or omega-CTX reduced it under mild hypoxic condition. When 30 to 50 mM KCl was applied to normoxic slices, a concentration-dependent increase in the extracellular cyclic GMP formation was observed. NS-7 blocked the cyclic GMP formation induced by 50 mM KCl but not by 30 to 40 mM KCl, whereas omega-CTX suppressed only the 30 mM KCl-evoked response. In primary neuronal culture, NS-7 reversed KCl-induced increase in intracellular Ca(2+) in which the inhibition was marked when the KCl concentration was increased. These findings suggest that NS-7, unlike other neuroprotective compounds used in this study, is more effective in severe hypoxic injury. The highly voltage-dependent Ca(2+) channel blockade may contribute to the mode of neuroprotective action of NS-7.

Adenosine Triphosphate↗

PubMed1999

Involvement of cholinergic and GABAergic systems in the reversal of memory disruption by NS-105, a cognition enhancer.

The effects of (+)-5-oxo-D-prolinepiperidinamide monohydrate (NS-105) on the scopolamine-, electrolytic lesion of the nucleus basalis magnocellularis (NBM)-, AF64A-, baclofen-, cerebral ischemia- and electroconvulsive shock (ECS)-induced memory disruption in the passive avoidance response or radial arm maze tasks were investigated in rats. The effects of NS-105 were compared with those of aniracetam, bifemelane, idebenone, and indeloxazine in two tasks of the passive avoidance response. Furthermore, effects of NS-105 on in vivo release of acetylcholine (ACh) in the cerebral cortex, high-affinity choline uptake (HACU) of the cerebral cortex in rats with lesion of NBM, HACU of the hippocampus in rats treated with pentobarbital and activity of choline acetyltransferase (ChAT) of the cerebral cortex in rats with lesion of NBM were examined. NS-105 showed antiamnestic actions in a variety of animal models of cholinergic dysfunction employed in this study. Aniracetam improved memory disruption caused by scopolamine, but bifemelane, idebenone, and indeloxazine did not. NS-105 (10 mg/kg) showed the increase of ACh release from the cerebral cortex and the enhancement of HACU both in the cerebral cortex and hippocampus, but showed no change in activity of ChAT. NS-105 also reversed memory disruption induced by baclofen, a potent GABA(B) receptor agonist, but all of reference drugs did not. These results suggest that antiamnestic action of NS-105 is due to the facilitation of cholinergic neuronal activity and the suppression of GABA(B) receptor-mediated responses.

Acetylcholine↗

PubMed1999

Contractile responses to alpha1-adrenoceptor agonists in isolated human male and female urethra.

OBJECTIVE: To investigate the contractile responses mediated through alpha1-adrenoceptors in human urethra and to evaluate the effectiveness of NS-49 [(R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulphonanilide++ + hydrochloride], a novel alpha1-adrenoceptor agonist, against contraction of the human urethra. MATERIALS AND METHODS: The contractile responses were assessed in 10 male prostatic urethrae and six female urethrae. Antagonism was evaluated in the urethra using phenylephrine, a nonselective alpha1-adrenoceptor agonist, cumulatively applied > 20 min after applying 0.1 micromol/L prazosin or 0.1 micromol/L 5-methylurapidil, a selective alpha1A-adrenoceptor antagonist. Agonism was determined in both male and female urethrae to obtain the concentration-response curve for the agonist. RESULTS: Phenylephrine caused both male and female urethrae to contract, and showed high potency and efficacy. Prazosin antagonized these contractions with low affinity (apparent pKB of 8.30 in male urethrae). 5-Methylurapidil, also antagonized the contractions with low affinity (apparent pKB of 7.88 in male urethrae). Noradrenaline and phenylephrine caused both male and female urethrae to contract, with high potency and efficacy. A novel and selective alpha1A-and alpha1L-adrenoceptor agonist, NS-49, induced contractile responses with high potency and moderate efficacy, whereas methoxamine induced contractions with low potency and moderate efficacy. Norephedrine was a very weak contractile agonist. CONCLUSION: In the human urethra, phenylephrine-induced contractions were mediated through alpha1L-adrenoceptors and not through alpha1A-adrenoceptors. Contractions of the human urethra induced by NS-49 were also mediated mainly through alpha1L-adrenoceptors, with high potency and moderate efficacy. NS-49 may therefore be useful for the treatment of urinary stress incontinence, with minimal side-effects because it has subtype selectivity.

Adrenergic alpha-Agonists↗