| Autor: |
Brodde, OttoErich, O'Hara, Naoki, Zerkowski, HansReinhard, Rohm, Norbert |
| Zdroj: |
Journal of Cardiovascular Pharmacology; November 1984, Vol. 6 Issue: 6 p1184-1191, 8p |
| Abstrakt: |
We investigated properties of catecholaminesensitive adenylate cyclase in membranes from human right atria. Basal adenylate cyclase was activated by Mg2ions and guanyl nucleotides GppNHp, GTP in a concentrationdependent manner guanyl nucleotide activation was strongly dependent on the presence of Mg2ions. Catecholamines stimulated adenylate cyclase activity in the following order of potency − isoprenaline > − adrenaline − noradrenaline > phenylephrine, indicating that, in human right atrium, 1adrenoceptors predominate. The 1agonist dobutamine and the 2agonists fenoterol and procaterol activated adenylate cyclase with an intrinsic activity of 0.50.7 isoprenaline 1.0. Adenylate cyclase activation by dobutamine or procaterol was notadditive with the activation induced by isoprenaline. On the contrary, combination of dobutamine 100 Mand procaterol 10 Mresulted in activation of adenylate cyclase which was not different from that evoked by saturating concentration of isoprenaline 10 M, indicating that dobutamine 1and procaterol 2produce adenylate cyclase activation through stimulation of different adrenoceptor subtypes. The 2selective antagonist ICI 118,551 was much more potent in inhibiting procaterol than isoprenalinestimulated adenylate cyclase activity, whereas the 1selective antagonist betaxolol inhibited isoprenalinestimulated activity more potently. We conclude that in human right atrium, both1and 2adrenoceptors are functionally coupled to the adenylate cyclase system. |
| Databáze: |
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