Pharmacological inhibition of AMP-deaminase in rat cardiac myocytes.

Because mutation of AMP deaminase 1 gene leading to reduced AMP deaminase activity may result in protection of cardiac function in patients with heart disease, inhibitors of AMP deaminase (AMPD) may have therapeutic applications. This study evaluated the effect of a specific inhibitor of AMP deaminase 3-[2-(3-carboxy-4-bromo-5,6,7,8-tetrahydronaphthyl)ethyl]-3,6,7,8-tetrahydroimidazo [4,5-d][1,3]diazepin-8-ol (AMPDI) on the isolated human enzyme and on nucleotide catabolism in rat cardiomyocytes. AMPDI effectively inhibited isolated human AMPD with an IC(50) = 0.5 micro M. AMPDI was much less effective with isolated cardiomyocytes (IC(50) = 0.5 mM). AMPDI is a very effective inhibitor of AMPD that despite lower efficiency in the cell system examined could be useful for in vivo studies.

Comparative studies of antiplatelet activity of nonsteroidal antiinflammatory drugs and new pyrazine CH- and NH-acids.

Nine known nonsteroidal antiinflammatory drugs (NSAID) and three new pyrazine derivatives possessing an active methylene moiety (pyrazine CH/NH-acids) were tested with regards to their in vitro and in vivo antiplatelet activity. Concentrations of the agents were determined which caused 25% and 50% inhibition of aggregation of human blood platelets induced by fixed concentrations of ADP, collagen and epinephrine. The in vivo test consisted in determination of percent protection of mice from pulmonary microembolism caused by injection of a mixture of collagen and epinephrine. The in vitro antiaggregatory activity of the agents studied was rather low, excepting the inhibition of the collagen-induced aggregation by ketoprofen. Several NSAID and two new pyrazine CH/NH-acids appeared highly potent antithrombotic agents in vivo. Activity of NSAID expressed as percent protection against lung thromboembolism in the mouse was demonstrated to depend quantitatively on acid properties of the agents. The new chemical class of pharmacologically active agents, pyrazine CH/NH-acids, offers an original pharmacophore which is distinctive from the carboxylic or enolic functionalities typical for the established NSAID, and as such, may be devoid of some disadvantages of known antiplatelet drugs.

Pyrazine CH- and NH-acids. Antithrombotic activity and chromatographic behaviour.

1. A series of newly synthesized pyrazine CH- and NH-acids was subjected to analytical and pharmacological studies. 2. The compounds were chromatographed in HPLC systems employing three reversed-phase columns and methanol-buffer solvents of various composition at acidic, neutral and alkaline pH. 3. Chemometrical analysis by the principal component method allowed for ordering of the compounds on a plane determined by the first two principal component axes. 4. Pharmacological tests were done for representatives of the series of compounds. 5. An in vivo antithrombotic assay on mice proved diversified bioactivity within the group of agents. 6. Attempts were undertaken to relate chromatographic behaviour to antithrombotic activity. 7. Based on the results obtained, an approach was proposed to reduce the number of pharmacological tests in selecting the most promising agents.