A1 Adenosine Receptor Modulation of Adenylyl Cyclase of a Deep-living Teleost Fish, Antimora rostrata

Abstract

Low temperatures and high hydrostatic pressures are typical of the deep sea. The effects of these parameters on transmembrane signal transduction were determined through a study of the A1 adenosine receptor-inhibitory guanine nucleotide binding protein-adenylyl cyclase system in brain membranes of the bathyal teleost fish, Antimora rostrata (Moridae). The components of this system were analyzed at 5°C and 1 atm, and the role of the A1 receptor in the modulation of adenylyl cyclase was determined. The A1 selective radioligand N6-[3H]cyclohexyladenosine bound saturably, reversibly, and with high affinity. The Kd of N6-[3H]cyclohexyladenosine estimated from kinetic measurements was 1.11 nM; the Kd determined from equilibrium binding was 4.86 nM. [32P]ADP-ribosylation of brain membranes by pertussis toxin labeled substrates with apparent molecular masses of 39,000 to 41,000 Da. Basal adenylyl cyclase activity was inhibited in a concentration-dependent manner by the A1 adenosine receptor agonist N6-cyclopentyladenosine (IC50 = 5.08 μM). The inhibition of adenylyl cyclase activity was dependent upon GTP. Basal adenylyl cyclase activity was unaffected by 272 atm of pressure. The efficacy of 100 μM N6-cyclopentyladenosine as an inhibitor of adenylyl cyclase was the same at atmospheric pressure and at 272 atm. The inhibition of adenylyl cyclase by the agonist 5'-N-ethylcarboxamidoadenosine (100 μM) at 272 atm was twice that observed at atmospheric pressure. Although consideration of the effects of low temperature and high hydrostatic pressure on acyl chain order suggest that deep-sea conditions will perturb membrane function, signal transduction by the A1 receptor system of the bathyal fish A. rostrata is not disrupted by deep-sea conditions.

Pertussis Toxin in the A10 Region Increases Dopamine Synthesis and Metabolism

“…[32P]ADP-ribosylation of G proteins ADP-ribosylation of GTP-binding proteins followed the procedures described by Ribeiro-Net0 et al (1985) and Greenberg et al (1987), as modified by Siebenaller and Murray (1990).…”

Distribution and biology of blue hake, Antimora rostrata (Pisces: Moridae), along the mid-Atlantic Ridge and off Greenland

“…Numerous studies include references to A. rostrata (Campbell et al, 1980;Siebenaller and Murray, 1990;Gauldie et al, 1991;Baily et al, 2003) but none offers a comprehensive account of its distribution and biology. General species characteristics (Iwamoto, 1975;Small, 1981), information on distribution and abundance from selected geographical areas (Wenner and Musick, 1977;Gordon and Duncan, 1985a;Kulka et al, 2003), and biological data (Magnússon, 2001;Kulka et al, 2003) have been presented.…”

Differential Susceptibility of Guanine Nucleotide-binding Proteins to Pertussis Toxin-catalyzed ADP-ribosylation in Brain Membranes of Two Congeneric Marine Fishes

“…We observed previously that the extent of [32P]ADPribosylation produced by a fixed concentration of pertussis toxin is different in the two Sebastolobus species (Siebenaller and Murray, 1990;Siebenaller el al.. 1991). Brain membranes from the deeper-living S. altivelis incorporate more [32P]ADP than S. alaseanus membranes (Siebenaller et nl.. 1991).…”