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. Author manuscript; available in PMC: 2021 Nov 26.
Published in final edited form as: Am J Physiol Heart Circ Physiol. 2003 May 22;285(3):H1040–H1047. doi: 10.1152/ajpheart.00981.2002

Fig. 4.

Fig. 4.

Responses to intracoronary bolus ADP injections. A: P1 receptor blockade by 8-SPT shifts the ADP dose-response curve moderately to the right, indicating some contribution by AMP and/or adenosine. B: after P1 receptor blockade with 8-SPT, 50 μM N6-methyl-2′-deoxyadenosine 3′,5′-bisphosphate (MRS 2179) severely inhibits vasodilation to 2-methylthio-ADP (2-MeS-ADP), confirming that MRS 2179 is an effective P2Y1 receptor antagonist. C: after P1 receptor blockade with 8-SPT, MRS 2179 shifts the ADP dose-response curve further rightward, indicating a contribution by P2Y1 receptors. The P2Y1 component is especially prominent at low ADP concentrations, where P1 receptor blockade has little effect (A). D: ADP responses are stable over time. Concentrations indicate the concentration in the 25-μl bolus injectate. The width of the horizontal bar on the experimental dose-response curve indicates the difference in rightward shift in the 2 hearts. *P < 0.01 vs. the ADP time-control experiment.