Biochem/physiol Actions

SLV320 is an orally active, high-affinity adenosine receptor A1 antagonist (pKi = 9.0 against 3H-DPCPX for binding human A1R and 8.6 against 3H-CCPA for binding rat A1R) that exhibits higher A1R-selectivity than DPCPX over other adenosine receptor subtypes (Fold-selectivity/subtypes = 200/hA3, 398/hA2a, 3981/hA2b). SLV320 displays much reduced or little affinity toward a panel of 94 other receptors and no inhibitory activity against PDE1-6 (IC50 ≥1 μM). SLV320 selectively reduces A1R-mediated bradycardia (ED50 = 0.49 mg/kg via p.o. or 0.25 mg/kg via i.v. 10 min prior to 100 μg/kg adenosine i.v. challenge), but not A2R-dependent hypotension (up to 2 mg/kg) among adenosin-challenged rats. When administered via food intake, SLV320 efficacy is demonstrated in experimental models of chronic renal failure (CRF; 10 mg/kg/day) and liver cirrhosis (5.1 mg/kg/day p.o.) in rats in vivo.