5.The pharmacology of two novel long-acting phosphodiesterase 3/4 inhibitors, RPL554 9,10-dimethoxy-2(2,4,6-trimethylphenylimino)-3-(N-carbamoyl-2-aminoethy l)-3,4,6,7-tetrahydro-2H-pyrimido6,1-aisoquinolin-4-one and RPL565 6,7-dihydro-2-(2,6-diisopropylphenoxy)-9,10-dimethoxy-4H...