Biphasic increase of gap junction coupling induced by dipyridamole in the rat aortic A-10 vascular smooth muscle cell line
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The rat aortic smooth muscle cell line A-10 was used to investigate the effect of dipyridamole on the gap junction coupling of smooth muscle cells. The scrape loading/dye transfer (SL/DT) technique revealed that dipyridamole concentrations between 5 μM and 100 μM significantly increased gap junction coupling. The adenosine receptor antagonist MRS 1754, as well as the PKA inhibitors Rp-cAMPS and H-89 were able to inhibit the dipyridamole-related increase in coupling, while forskolin and Br-cAMP also induced an enhancement of the gap junction coupling. Regarding the time-dependent behaviour of dipyridamole, a short-term effect characterised by an oscillatory reaction was observed for application times of less than 5 h, while applications times of at least 6 h resulted in a long-term effect, characterised by a constant increase of gap junction coupling to its maximum levels. This increase was not altered by prolonged presence of dipyridamole. In parallel, a short application of dipyridamole for at least 15 min was found to be sufficient to evoke the long-term effect measured 6 h after drug washout. We propose that in both the short-term and long-term effect, cAMP-related pathways are activated. The short-term phase could be related to an oscillatory cAMP effect, which might directly affect connexin trafficking, assembly and/or gap junction gating. The long-term effect is most likely related to the new expression and synthesis of connexins. With previous data from a bovine aortic endothelial cell line, the present results show that gap junction coupling of vascular cells is a target for dipyridamole.
KeywordscAMP Dipyridamole Gap junction PKA Vascular smooth muscle cells
8-Bromoadenosine-3′ 5′-cyclic monophosphate
Cyclic adenosine-3′ 5′-cyclic monophosphate
Equilibrative nucleoside transporter
Protein kinase A
Rp-adenosine-3′,5′-cyclic mono-phosphorothioate triethylamine salt
Scrape loading/dye transfer
This work was supported by Boehringer Ingelheim International GmbH. The authors thank Prof. Dr. Wolfgang Eisert for discussion and comments on the manuscript.
- Eisert WG (2006) Dipyridamole. In: Michelson AD (ed) Platelets, 2 edn. Amsterdam, pp 1165–1179Google Scholar
- ESPRIT Study Group, Halkes PH, van Gijn J, et al. Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial. 2006 May; 367, 9523, pp 1665–73Google Scholar