Comparison of effects of MgCl2 and Gpp(NH)p on antagonist and agonist radioligand binding to adenosine A1 receptors.

Aim: To investigate modulation of antagonist and agonist binding to adenosine A1 receptors by MgCl2 and 5 -guanylimidodiphosphate (Gpp(NH)p) using rat brain membranes and the A1 antagonist [3H]-8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) and the A1 agonist [3H]-2-chloro-N6-cyclopentyladenosine ([3H]CCPA).

Methods: Parallel saturation and inhibition studies were performed using well-characterised radioligand binding assays and a Brandel Cell Harvester.

Results: MgCl2 produced a concentration-dependent decrease (44%), whereas Gpp(NH)p increased [3H]DPCPX binding (19%).

Target discovery and validation in the post-genomic era.

The recent publication of the human genome sequence provides an opportunity both to combat diseases that are presently considered as pharmaceutically intractable and also to improve current therapies for many common human diseases. The identification of every human gene by ongoing bioinformatic efforts has the potential, when combined with functional genomic approaches, to pinpoint the molecular basis of every human disease, and to discover appropriate intervention points. This exciting prospect is directly relevant to the successful development of effective therapeutics because the past record of drug discovery suggests that 30%-40% of experimental drugs fail because an inappropriate biological target was pursued.

Nitric-oxide-synthase-mediated cyclic guanosine monophosphate production in neonatal rat cerebellar prisms is resistant to calcineurin inhibition.

Although the macrolide immunosuppressant tacrolimus (FK506) is neuroprotective in animal models of focal and global cerebral ischaemia, the mechanism of this action is not known. FK506 inhibits the protein phosphatase calcineurin, whose substrates can include nitric oxide synthase (NOS), and the neuroprotective effect of FK506 has been attributed to inhibition of NOS activity. We have examined nitric oxide-mediated cyclic guanosine monophosphate (cGMP) accumulation in neonatal rat cerebellar prisms.