Identification of α-1L Adrenoceptor in Rabbit Ear Artery

Hiraizumi-Hiraoka, Yasuko; Tanaka, Takashi; Yamamoto, Hideya; Suzuki, Fumiko; Muramatsu, Ikunobu

doi:10.1124/jpet.104.066985

Cited by 34 publications

(42 citation statements)

References 32 publications

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“…1A), it is not likely that the high density estimated in the present study is an overestimation due to nonspecific accumulation of the radioligand into intact tissues and cells. Rather, underestimation may be caused by the conventional binding method with membrane preparations, as reported previously in the rat heart (16) and rabbit ear artery (21). We are now examining this discrepancy between different binding assay methods.…”

Section: If the Cells And Tissues Are Intact It Is Likely That Hydromentioning

confidence: 82%

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Assessment of Muscarinic Receptor Subtypes in Human and Rat Lower Urinary Tract by Tissue Segment Binding Assay

et al. 2008

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Abstract. Muscarinic receptors in the human and rat lower urinary tract (urinary bladder detrusor muscle and mucosa, and prostate) were identified by intact tissue segment binding assays with two radioligands, and the effects of prolonged receptor activation in vitro on muscarinic receptors were examined. Hydrophilic [3 H]-NMS and hydrophobic [ 3 H]-QNB bound to the detrusor muscle segments with the same density, suggesting that the muscarinic receptors were localized at the plasma membrane. While the density of muscarinic receptor was higher in detrusor muscle than in the bladder mucosa and prostate, there was no species-specific difference either in density or in subtype distribution (M 1 , M 2 , and M 3 subtypes in detrusor; M 2 and M 3 subtypes in bladder mucosa; and M 1 and M 2 subtypes in prostate). Incubation of detrusor strips with carbachol decreased [3 H]-NMS binding sites within 20 min, followed by a reduction of [ 3 H]-QNB binding sites after a 60-min lag phase. The loss of the binding sites over 3 h after carbachol treatment was the same (approximately 40%) for both radioligands. The present intact tissue segment binding assay reveals tissue-specific and plasma membrane distribution of distinct muscarinic receptor subtypes and their dynamic changes (internalization and down-regulation) in lower urinary tract of humans and rats.

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Section: If the Cells And Tissues Are Intact It Is Likely That Hydromentioning

confidence: 82%

“…In functional studies, antagonist affinity estimates (pK B values) were determined for a single concentration of antagonist by the concentration ratio method, as reported previously (21). We used a one-way analysis of variance (ANOVA), followed by Scheffe's post-hoc test, or Student's paired or unpaired t-test where appropriate.…”

Section: Data Analysesmentioning

confidence: 99%

Assessment of Muscarinic Receptor Subtypes in Human and Rat Lower Urinary Tract by Tissue Segment Binding Assay

et al. 2008

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“…Rather, as described above, a close relationship between a1L-adrenoceptor and a1A-adrenoceptor has been considered (Ford et al, 1997;Hiraizumi-Hiraoka et al, 2004;Morishima et al, 2008).…”

Section: Identification Of the Gene Encoding A 1l -Adrenoceptormentioning

confidence: 99%

Phenotype pharmacology of lower urinary tract α₁‐adrenoceptors

Nishimune

Yoshiki

Uwada

et al. 2012

British J Pharmacology

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Keywordsa1L-adrenoceptor; a1A-adrenoceptor; benign prostatic hyperplasia (BPH); stress urinary incontinence (SUI); lower urinary tract; phenotype pharmacology a1-Adrenoceptors are involved in numerous physiological functions, including micturition. However, the pharmacological profile of the a1-adrenoceptor subtypes remains controversial. Here, we review the literature regarding a1-adrenoceptors in the lower urinary tract from the standpoint of a1L phenotype pharmacology. Among three a1-adrenoceptor subtypes (a1A, a1B and a1D), a1a-adrenoceptor mRNA is the most abundantly transcribed in the prostate, urethra and bladder neck of many species, including humans. In prostate homogenates or membrane preparations, a1A-adrenoceptors with high affinity for prazosin have been detected as radioligand binding sites. Functional a1-adrenoceptors in the prostate, urethra and bladder neck have low affinity for prazosin, suggesting the presence of an atypical a1-adrenoceptor phenotype (designated as a1L). The a1L-adrenoceptor occurs as a distinct binding entity from the a1A-adrenoceptor in intact segments of variety of tissues including prostate. Both the a1L-and a1A-adrenoceptors are specifically absent from Adra1A (a1a) gene-knockout mice. Transfection of a1a-adrenoceptor cDNA predominantly expresses a1A-phenotype in several cultured cell lines. However, in CHO cells, such transfection expresses a1L-and a1A-phenotypes. Under intact cell conditions, the a1L-phenotype is predominant when co-expressed with the receptor interacting protein, CRELD1a. In summary, recent pharmacological studies reveal that two distinct a1-adrenoceptor phenotypes (a1A and a1L) originate from a single Adra1A (a1a-adrenoceptor) gene, but adrenergic contractions in the lower urinary tract are predominantly mediated via the a1L-adrenoceptor. From the standpoint of phenotype pharmacology, it is likely that phenotype-based subtypes such as the a1L-adrenoceptor will become new targets for drug development and pharmacotherapy. ---------------------------------------------------------------- LINKED ARTICLE IntroductionThe lower urinary tract is responsible for urine storage and voiding (Andersson and Wein, 2004). In mammalian species including humans, the bladder detrusor muscle contracts through a parasympathetic cholinergic mechanism during micturition (Abrams et al., 2006;Wess et al., 2007). Besides the importance of the cholinergic system as the major mechanism for bladder neck muscle tone control, the adrenergic systems play significant roles in the regulation of bladder neck tone (Fig. 1). During the storage phase, the urethra and outlet region of the bladder is contracted to Among impairments in urine storage, stress urinary incontinence (SUI) is recognized as one of the most frequently occurring conditions. Deficient urethral or bladder neck closure may result in this condition. However, drug treatments for SUI are scarce, at present (Andersson and Wein, 2004). The density of noradrenergic nerves increases markedly towards the bladder neck and ureth...

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“…However, tissue homogenization may cause changes in the receptor environment, resulting in measured properties that differ from those of the receptor in the native tissue. Recently, a binding assay that uses intact tissue segments was developed and was shown to be a powerful method for analysis of the inherent properties of receptors present in native tissues (7,15). In the intact segment binding assay, in contrast to conventional membrane binding assays, it is not necessary to consider either the yield loss of receptors or modification of the natural environment of receptors that may be caused upon tissue homogenization.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Novel Muscarinic Acetylcholine Receptors in Rat Cerebral Cortex by a Tissue Segment Binding Method

et al. 2010

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Abstract. Muscarinic acetylcholine receptors (mAChRs) of rat cerebral cortex were evaluated using a tissue segment radioligand binding assay. [3 H]-Quinuclidinyl benzilate (QNB, a hydrophobic ligand) specifically bound to mAChRs in the cortex segments. The total mAChRs level was approximately 2,000 fmol/mg protein, which was estimated after incubation for 120 min at 37°C or for 8 h at 4°C. These mAChRs were a mixture of high-and low-affinity sites for N-methylscopolamine (NMS) in a 70:30 ratio. In contrast, only a single high-affinity site for NMS was detected following incubation for 30 min at 37°C, whose abundance was about 70% of that of the total mAChRs. Atropine showed a single affinity for mAChRs under all conditions. These indicate that mAChRs are constitutively expressed not only on plasma membrane sites but also at intracellular sites in rat cerebral cortex and that the receptors at both sites have different affinities for NMS. Acetylcholine completely inhibited [ 3 H]-QNB binding to both mAChRs without any change in the subcellular distribution, suggesting the possibility that acetylcholine can access, and bind to, both mAChRs in intact tissue. Two different affinity states for acetylcholine were detected only in plasma membrane mAChRs at 37°C. The present study demonstrates a unique subcellular distribution, and distinct pharmacological profiles, of mAChRs in rat cerebral cortex.

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Identification of α-1L Adrenoceptor in Rabbit Ear Artery

Cited by 34 publications

References 32 publications

Assessment of Muscarinic Receptor Subtypes in Human and Rat Lower Urinary Tract by Tissue Segment Binding Assay

Assessment of Muscarinic Receptor Subtypes in Human and Rat Lower Urinary Tract by Tissue Segment Binding Assay

Phenotype pharmacology of lower urinary tract α₁‐adrenoceptors

Assessment of Novel Muscarinic Acetylcholine Receptors in Rat Cerebral Cortex by a Tissue Segment Binding Method

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Identification of α-1L Adrenoceptor in Rabbit Ear Artery

Cited by 34 publications

References 32 publications

Assessment of Muscarinic Receptor Subtypes in Human and Rat Lower Urinary Tract by Tissue Segment Binding Assay

Assessment of Muscarinic Receptor Subtypes in Human and Rat Lower Urinary Tract by Tissue Segment Binding Assay

Phenotype pharmacology of lower urinary tract α1‐adrenoceptors

Assessment of Novel Muscarinic Acetylcholine Receptors in Rat Cerebral Cortex by a Tissue Segment Binding Method

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Phenotype pharmacology of lower urinary tract α₁‐adrenoceptors