Inhibition by etazolate (SQ 20009) and cartazolate (SQ 65396) of adenosine-stimulated [3H]cAMP formation in [2-3H]adenine-prelabeled vesicles prepared from guinea pig cerebral cortex

Psychoyos, Stacy; Ford, C.; Phillipps, Mildred A.

doi:10.1016/0006-2952(82)90041-7

Cited by 21 publications

(2 citation statements)

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“…The pyrazolopyridines tracazolate, cartazolate, and etazolate (Ia, Ib, Ic) have been reported to inhibit 2-chloroadenosine-stimulated generation of cyclic AMP in guinea pig brain vesicular preparations at an A 2 receptor with estimated K i values of 13, 2.0 and 3.9 μM respectively [18]. Tracazolate was reported to have K i values versus binding of N 6 -[ 3 H]cyclohexyladenosine to brain membranes of various species ranging from 0.22 μM in calf, to 0.31 μM in rat, to 5.2 μM in human [17].…”

Section: Pyrazolopyridinesmentioning

confidence: 99%

“…Other classes of heterocyclic compounds exhibit antagonist activity at adenosine receptors. These include: 9-methyladenines [10,14], various pyrazolopyridines (etazolate, cartazolate, tracazolate) [15][16][17][18], various pyrazolopyrimidines [19,20], imidazopyrazines [21], a phenyl-substituted pyrazoloquinoline (CGS 8216) [22,23], a furyl-sub-stituted triazoloquinazoline (CGS 15943a) [24], a triazolopyridazine (CL218872) [15], various mesoionic analogs of xanthines [25], pteridin-2,4-diones (lumazine) and benzopteridin-2,4-diones [10,26], β-carbolines [15,27], barbiturates [28,29] and dibenzazepines (carbamazepine) [30][31][32][33]. A phenylaminoimidazoline, clonidine, has been reported to antagonize adenosine responses in physiological experiments [34].…”

Section: Introductionmentioning

confidence: 99%

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Non-xanthine heterocycles: Activity as antagonists of A1 and A2-adenosine receptors

Daly

Hong

Padgett

et al. 1988

Biochemical Pharmacology

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A variety of non-xanthine heterocycles were found to be antagonists of binding of [ 3 H]phenylisopropyladenosine to rat brain A 1 -adenosine receptors and of activation of adenylate cyclase via interaction of N-ethylcarboxarnidoadenosine with A 2 -adenosine receptors in human platelet and rat pheochromocytoma cell membranes. The pyrazolopyridines tracazolate, cartazolate and etazolate were several fold more potent than theophylline at both A 1 -and A 2 -adenosine receptors. The pyrazolopyridines, however, were still many fold less potent than 8-phenyltheophylline and other 8-phenyl-1,3-dialkylxanthines. A structurally related N 6 -substituted 9-methyladenine was also a potent adenosine antagonist with selectivity for A 1 receptors. None of several aryl-substituted heterocycles, including a thiazolopyrimidine, imidazopyridines, benzimidazoles, a pyrazoloquinoline, a mesoionic xanthine analog and a triazolopyridazine exhibited the high potency typical of 8-phenyl-1,3-dialkylxanthines. A furyl-substituted triazoloquinazoline was very potent at both A 1 and A 2 receptors. A pteridin-2,4-dione, 1,3-dipropyllumazine, was somewhat less potent than theophylline at A 1 -and A 2 -adenosine receptors, whereas 1,3-dimethyllumazine was much less potent. A benzopteridin-2,4-dione, alloxazine, was somewhat more potent than theophylline. Other heterocycles with antagonist activity were the dibenzazepine carbamazepine and β-carboline-3-ethyl carboxylate. The phenylimidazoline clonidine had no activity, whereas a related dihydroxyphenylimidazoline was a weak noncompetitive adenosine antagonist.Xanthines, such as theophylline, caffeine and various 8-aryl-1,3-dialkylxanthines, have been widely used as antagonists of A 1 and A 2 -adenosine receptors [1]. The 8-aryl-1,3-dialkylxanthines are very potent at both subclasses of adenosine receptors [2][3][4][5][6][7][8][9][10][11]. Certain 8-aryl-1,3-dipropylxanthines exhibit selectivity for A 1 receptors [4,8,9] and certain caffeine analogs exhibit some selectivity for A 2 receptors [12,13]. Other classes of heterocyclic compounds exhibit antagonist activity at adenosine receptors. These include: 9-methyladenines [10,14], various pyrazolopyridines (etazolate, cartazolate, tracazolate) [15][16][17][18], various pyrazolopyrimidines [19,20], imidazopyrazines [21], a phenyl-substituted pyrazoloquinoline (CGS 8216) [22,23], a furyl-sub-stituted triazoloquinazoline (CGS 15943a) [24], a triazolopyridazine (CL218872) [15], various mesoionic analogs of xanthines [25], pteridin-2,4-diones (lumazine) and benzopteridin-2,4-diones [10,26], β-carbolines [15,27], barbiturates [28,29] and dibenzazepines (carbamazepine) [30][31][32][33]. A phenylaminoimidazoline, clonidine, has been reported to antagonize adenosine responses in physiological experiments [34].The non-xanthine adenosine antagonists have been largely neglected in behavioral and physiological studies, and little is known of structure-activity relationships within such METHODS MaterialsThe sources from which we obtained our mat...

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Section: Pyrazolopyridinesmentioning

confidence: 99%