Figure 2.
(A) Effect of the A1-adenosine receptor agonist R-PIA (1 μM) on force of contraction in electrically driven left atria from wild-type mice and A1-adenosine receptor overexpressing mice (line 1). Numbers in brackets indicate number of individual left atria. Asterisks indicate significant difference between Ctr (no addition of R-PIA) and treatment. First, the preparations were treated for 30 min with adenosine deaminase. Then R-PIA, as indicated, was added and incubation was for further 10 min. Thereafter, force of contraction was measured in mN (milli Newton, ordinate). (B) Effect of the A1-adenosine receptor agonist R-PIA (1 μM) in the presence of the A1-adenosine receptor antagonist DPCPX (1 μM) on force of contraction in electrically driven left atria from wild-type and A1-adenosine receptor overexpressing mice (line 1). First, the preparations were treated for 30 min with adenosine deaminase. Then, where indicated DPCPX was added. 30 min later, R-PIA (R-PIA+DPCPX) was added for 10 min. Ordinate: force of contraction in per cent of values after 30 min of treatment with adenosine deaminase (ADA). Numbers in brackets indicate number of individual left atria. Asterisks indicate a significant difference between Ctr (no addition of R-PIA or DPCPX) and treatment (DPCPX+R-PIA).