Figure 1.

Effects of adenosine (Ado, 100 μM), acetylcholine (ACh, 10 μM) and diadenosine pentaphosphate (Ap₅A, 100 μM) on spontaneous cycle length of rabbit Langendorff-perfused hearts. (a) Illustrates a typical recording representative for six isolated hearts. Perfusion with either agonist induced a prolonging of spontaneous atrial cycle length which was assessed by measurement of A–A interval. (b) Shows the mean cycle length during control and during agonist perfusion after a stable plateau of bradycardia was reached.