Evidence for the presence of A1 and A2 adenosine receptors in the ventral aorta of the dogfish shark, Squalus acanthias

1992 ◽  
Vol 162 (2) ◽  
pp. 179-183 ◽  
Author(s):  
David H. Evans
Keyword(s):  
Adenosine Receptors ◽  
Squalus Acanthias ◽  
Ventral Aorta ◽  
Dogfish Shark ◽  
A2 Adenosine Receptors

A prostaglandin, not NO, mediates endothelium-dependent dilation in ventral aorta of shark (Squalus acanthias)

1998 ◽  
Vol 274 (4) ◽  
pp. R1050-R1057 ◽  
Author(s):  
David H. Evans ◽  
Mark P. Gunderson
Keyword(s):  
Squalus Acanthias ◽  
Current Evidence ◽  
Shark Species ◽  
No Donor ◽  
Paracrine Factors ◽  
A 23187 ◽  
Ventral Aorta ◽  
Dogfish Shark ◽  
Synthase Inhibitor

In mammals, the vascular endothelium releases a variety of paracrine factors, including the vasodilatory prostaglandin (PG)I2 and nitric oxide (NO), which is generally accepted as the major endothelium-derived relaxing factor (EDRF) in mammals. Current evidence for the vascular NO-EDRF system in fishes is contradictory. In addition, the role of PGs in the control of fish vascular tension is also unclear. We have utilized isolated rings of the ventral aorta of the spiny dogfish shark to examine the ability of various components of the NO system to dilate this vessel. Neither the NO precursorl-arginine, the NO donor sodium nitroprusside, nor NO itself dilated the rings. The Ca2+ ionophore A-23187 did produce an endothelium-dependent dilation that was not inhibited by the NO synthase inhibitor N G-nitro-l-arginine methyl ester but was inhibited by the cyclooxygenase inhibitor indomethacin, suggesting that PGs are involved. PGE1 and carbaprostacyclin, but not PGI2, produced concentration-dependent dilation, and intact aortic rings secreted five times as much PGI2as PGE in both the unstimulated state and after stimulation with A-23187. Our data suggest strongly that a PG, most probably PGI2, is the EDRF in the ventral aorta of this shark species.

A1 and A2 Adenosine Receptors in Synovial Cells from Patients with Rheumatic Diseases

1989 ◽  
pp. 429-433 ◽  
Author(s):  
Claudia Martini ◽  
Gino Giannaccini ◽  
Antonio Lucacchini ◽  
Laura Bazzichi ◽  
Annalia Soletti ◽  
...  
Keyword(s):  
Rheumatic Diseases ◽  
Adenosine Receptors ◽  
Synovial Cells ◽  
A2 Adenosine Receptors

Homospecific regulation of A1 and A2 adenosine receptors

1990 ◽  
Vol 22 ◽  
pp. 431
Author(s):  
A.M. Rosati ◽  
C. Florio ◽  
U. Traversa ◽  
R. Vertua
Keyword(s):  
Adenosine Receptors ◽  
A2 Adenosine Receptors

Characterization of an endothelin ET(B) receptor in the gill of the dogfish shark Squalus acanthias

1999 ◽  
Vol 202 (24) ◽  
pp. 3605-3610 ◽  
Author(s):  
D.H. Evans ◽  
M.P. Gunderson
Keyword(s):  
Blood Vessels ◽  
Gill Tissue ◽  
Squalus Acanthias ◽  
Single Site ◽  
Acid Base Balance ◽  
Ion Regulation ◽  
Base Balance ◽  
Dogfish Shark ◽  
Kinetics Of

Endothelins (ETs) are potent vasoconstrictive peptides that are secreted by the vascular endothelium and other tissues in vertebrates. Previous studies have demonstrated that ETs are expressed in a variety of fish tissues and contract various blood vessels. In order to determine if receptors for ET are expressed in fish gill tissue, we examined the binding kinetics of (125)I-labeled, human ET-1 to membrane fragments isolated from the gill of the dogfish shark, Squalus acanthias. (125)I-ET-1 bound at a single site, with a dissociation constant (K(d)) and binding site number (B(max)) very similar to those described in a variety of mammalian blood vessels. ET-1 and ET-3 competed equally with (125)I-ET-1, suggesting that the receptor was ET(B), which has been shown in mammalian systems to bind to both ligands equally. The ET(B)-specific agonists sarafotoxin S6c, IRL-1620, and BQ-3020 also competed against (125)I-ET-1 at a single site, supporting this hypothesis. We conclude that the shark gill expresses an ET(B) receptor with substantial homology to the mammalian receptor and that ET may play an important role in modulating such vital gill functions as gas exchange, ion regulation, acid-base balance, and excretion of nitrogen.

Fluorescein-methotrexate transport in dogfish shark (Squalus acanthias) choroid plexus

2006 ◽  
Vol 291 (2) ◽  
pp. R464-R472 ◽  
Author(s):  
Carsten H. Baehr ◽  
Gert Fricker ◽  
David S. Miller
Keyword(s):  
Protein Kinase ◽  
Choroid Plexus ◽  
Organic Anion ◽  
Basolateral Membrane ◽  
Fold Increase ◽  
Squalus Acanthias ◽  
Cellular Accumulation ◽  
Vascular Space ◽  
Dogfish Shark ◽  
Tissue Compartments

The vertebrate choroid plexus removes potentially toxic metabolites and xenobiotics from cerebrospinal fluid (CSF) to blood for subsequent excretion in urine and bile. We used confocal microscopy and quantitative image analysis to characterize the mechanisms driving transport of the large organic anion, fluorescein-methotrexate (FL-MTX), from bath (CSF-side) to blood vessels in intact lateral choroid plexus from dogfish shark, Squalus acanthias, an evolutionarily ancient vertebrate. With 2 μM FL-MTX in the bath, steady-state fluorescence in the subepithelium/vascular space exceeded bath levels by 5- to 10-fold, and fluorescence in the epithelial cells was slightly below bath levels. FL-MTX accumulation in both tissue compartments was reduced by NaCN, Na removal, and ouabain, but not by a 10-fold increase in medium K. Certain organic anions, e.g., probenecid, MTX, and taurocholate, reduced FL-MTX accumulation in both tissue compartments; p-aminohippurate and estrone sulfate reduced subepithelial/vascular accumulation, but not cellular accumulation. At low concentrations, digoxin, leukotriene C4, and MK-571 reduced fluorescence in the subepithelium/vascular space while increasing cellular fluorescence, indicating preferential inhibition of efflux over uptake. In the presence of 10 μM digoxin (reduced efflux, enhanced cellular accumulation), cellular FL-MTX accumulation was specific, concentrative, and Na dependent. Thus transepithelial FL-MTX transport involved the following two carrier-mediated steps: electroneutral, Na-dependent uptake at the apical membrane and electroneutral efflux at the basolateral membrane. Finally, FL-MTX accumulation in both tissue compartments was reduced by phorbol ester and increased by forskolin, indicating antagonistic modulation by protein kinase C and protein kinase A.

Control of rectal gland secretion by blood acid–base status in the intact dogfish shark (Squalus acanthias)

2007 ◽  
Vol 156 (2) ◽  
pp. 220-228 ◽  
Author(s):  
Chris M. Wood ◽  
R. Stephen Munger ◽  
Jill Thompson ◽  
Trevor J. Shuttleworth
Keyword(s):  
Squalus Acanthias ◽  
Gland Secretion ◽  
Rectal Gland ◽  
Acid Base ◽  
Acid Base Status ◽  
Dogfish Shark

The second extracellular loop of GPCRs determines subtype-selectivity and controls efficacy as evidenced by loop exchange study at A2 adenosine receptors

2013 ◽  
Vol 85 (9) ◽  
pp. 1317-1329 ◽  
Author(s):  
Benjamin F. Seibt ◽  
Anke C. Schiedel ◽  
Dominik Thimm ◽  
Sonja Hinz ◽  
Farag F. Sherbiny ◽  
...  
Keyword(s):  
Adenosine Receptors ◽  
Extracellular Loop ◽  
Subtype Selectivity ◽  
Exchange Study ◽  
A2 Adenosine Receptors
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