Localization of receptors for natriuretic peptide and endothelin in the duct of the epididymis of the freshwater turtle
| Autor: | Sung Zoo Kim, Sook Jeong Lee, Seon Young Kang, Kyung Woo Cho |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Male
medicine.medical_specialty medicine.drug_class Nerve Tissue Proteins Biology Ligands chemistry.chemical_compound Endocrinology Internal medicine Guanosine monophosphate medicine Natriuretic peptide Animals Receptor Cyclic GMP Epididymis BQ-123 Endothelin-1 Receptors Endothelin BQ-788 In vitro Peptide Fragments Turtles medicine.anatomical_structure chemistry Guanylate Cyclase Autoradiography Animal Science and Zoology Endothelin receptor Receptors Atrial Natriuretic Factor Atrial Natriuretic Factor Densitometry |
| Zdroj: | General and comparative endocrinology. 118(1) |
| ISSN: | 0016-6480 |
| Popis: | The presence of receptor subtypes for natriuretic peptides (NPs) and endothelin (ET) in the epididymis of the freshwater turtle, Amyda japonica , was examined by quantitative in vitro autoradiography using iodinated mammalian-type atrial NP ( 125 I-ANP (1–28) ), phylogenically conserved C-type NP ( 125 I-[Tyr 0 ]-CNP (1–22) ), and ET-1 ( 125 I-ET-1) as radiolabeled ligands. To characterize NP receptor (NPR) subtypes, we also performed an activation of particulate guanylyl cyclase (GC) in membranes of the epididymis by NPs. Specific 125 I-ANP (1–28) and 125 I-[Tyr 0 ]-CNP (1–22) bindings were localized in surrounding smooth muscle cell layer of the duct of the epididymis with an apparent dissociation constant ( K d ) of 0.84 ± 0.15 and 1.74 ± 0.39 nM and a maximal binding capacity ( B max ) of 0.47 ± 0.11 and 0.08 ± 0.01 fmol/mm 2 , respectively. Bindings of 125 I-ANP (1–28) and 125 I-[Tyr 0 ]-CNP (1–22) to these sites were also displaced by des[Gln 18 ,Ser 19 ,Gly 20 , Leu 21 ,Gly 22 ]ANF (4–23) , a specific ligand of the NP clearance receptor. Production of 3′,5′-cyclic guanosine monophosphate by particulate GC in membranes of the epididymis was stimulated by ANP (1–28) , BNP (1–26) , and CNP (1–22) . Receptor subtypes for ET in the epididymis were characterized by competition with BQ 123 and BQ 788 as specific antagonists for ET receptors, type A (ET A ) and type B (ET B ) subtypes, respectively. Specific 125 I-ET-1 bindings were localized in the smooth muscle cell layer of the duct of the epididymis with K d and B max of 0.21 ± 0.03 nM and 0.52 ± 0.05 fmol/mm 2 , respectively. These specific bindings were potently inhibited in a dose-dependent manner by BQ 123, whereas BQ 788 (10 μM) was not in competing for specific 125 I-ET-1 bindings in this structure. Therefore, these results indicate that specific NP and ET receptors are localized in surrounding smooth muscle cells of the duct of the epididymis of the freshwater turtle. It is also suggested that biological and clearance NPR-like subtypes coexist in these cells, and the predominant ET receptor subtype in this tissue is the ET A -like receptor. The localization of specific receptors for NPs and ET in the epididymis may be involved in the control of the transport of sperm in the freshwater turtle. |
| Databáze: | OpenAIRE |
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