Binding kinetics and sequencing of hepatic α1-adrenergic receptors in two marine teleosts, Mackerel (Scomber scombrus) and Anchovy (Engraulis encrasicolus)
✍ Scribed by Elena Fabbri; Xi Chen; Antonio Capuzzo; Thomas W. Moon
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2008
- Tongue
- English
- Weight
- 751 KB
- Volume
- 309A
- Category
- Article
- ISSN
- 1932-5223
- DOI
- 10.1002/jez.441
No coin nor oath required. For personal study only.
✦ Synopsis
Liver a 1 -adrenoceptors (ARs) are demonstrated, or at least hypothesized, in freshwater and brackish-water teleosts, whereas no data are available for marine teleosts. This study evaluates the presence of a 1 -ARs in the liver of two marine teleosts, the anchovy Engraulis encrasicolus and the mackerel Scomber scombrus, and examines on a broad scale the possibility that habitats posing different challenges also influence phenotypic trait selection. Binding assays were performed also on liver membranes from the carp Cyprinus carpio as a direct comparison with a freshwater species. Scatchard analysis of [ 3 H]prazosin binding to purified liver membranes from anchovy, mackerel and carp resulted in K d values of 1.5170.085, 1.2670.098, and 2.6170.22 nM, and B max values of 87.479.12, 7778.29, and 115.2273.31 fmol/mg protein, respectively. Thus, a 1 -ARs of the two marine teleosts showed higher [ 3 H]prazosin affinity compared with those of the freshwater/brackish-water fish studied thus far, whereas the number of liver binding sites did not differ significantly from that of carp, eel or trout. A preliminary phylogeny based on amino acid sequence analysis indicated the presence of at least an a 1A -AR in mackerel and an a 1D -AR in both anchovy and mackerel. This is the first indication of a 1 -AR subtypes in any marine species, but further studies are needed to ascertain the physiological role of these a 1 -ARs in these two marine species.