Article date: May 1985
By: Geoffrey Burnstock, Charles H.V. Hoyle in Volume 85, Issue 1, pages 291-296
1,3‐Dipropyl‐8‐(2‐amino‐4‐chlorophenyl)xanthine (PACPX) was examined for its ability to antagonize adenosine acting on the A1 and A2 subclasses of the P1‐purinoceptor. A1‐purinoceptors were studied in the isolated, driven left atria of the guinea‐pig, and A2‐purinoceptors in the isolated, carbachol‐contracted taenia coli of the guinea‐pig.
PACPX antagonized the actions of adenosine in both types of preparation and was a more potent antagonist than 8‐phenyltheophylline.
The antagonism at the A2‐purinoceptor was competitive with a pA2 of 5.95.
The antagonism at the A1‐purinoceptor was not competitive, although antagonism at the A1‐purinoceptor was greater than that at the A2‐purinoceptor, based on a comparison of pD2 values.
The manner of antagonism of PACPX on the A1‐purinoceptors of the heart was different from that found for the A1‐receptors in bovine brain, implying that there is a fundamental difference between these central and peripheral A1 subclasses of P1‐purinoceptor.
1,3‐Dipropyl‐8‐(2‐amino‐4‐chlorophenyl)xanthine (PACPX) was examined for its ability to antagonize adenosine acting on the A1 and A2 subclasses of the P1‐purinoceptor. A1‐purinoceptors were studied in the isolated, driven left atria of the guinea‐pig, and A2‐purinoceptors in the isolated, carbachol‐contracted taenia coli of the guinea‐pig.
PACPX antagonized the actions of adenosine in both types of preparation and was a more potent antagonist than 8‐phenyltheophylline.
The antagonism at the A2‐purinoceptor was competitive with a pA2 of 5.95.
The antagonism at the A1‐purinoceptor was not competitive, although antagonism at the A1‐purinoceptor was greater than that at the A2‐purinoceptor, based on a comparison of pD2 values.
The manner of antagonism of PACPX on the A1‐purinoceptors of the heart was different from that found for the A1‐receptors in bovine brain, implying that there is a fundamental difference between these central and peripheral A1 subclasses of P1‐purinoceptor.
DOI: 10.1111/j.1476-5381.1985.tb08859.x
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