Isoflurane-induced protection against myocardial stunning is independent of adenosine 1 (A(1)) receptor in isolated rat heart

Volatile anaesthetics can pharmacologically enhance the recoveryof stunned myocardium, but the mechanism is still unknown. Thisstudy sought to determine whether isoflurane attenuates myocardialstunning, and whether the myocardial protection of isofluraneis mediated by adenosine A₁ receptors. Five groups (n=8) ofisolated rat hearts were studied in the Langendorff apparatus.The control groups underwent 20-min ischaemia with or withoutadenosine receptor antagonist (DPCPX, A₁selective) treatment(Cont group and DPCPX group). In the isoflurane groups, isoflurane(1.5 MAC) was present throughout the experiment (Iso group)and DPCPX (200 nM) was administered from 10 min before ischaemia(Iso+DPCPX(pre-I) group) or the beginning of reperfusion (Iso+DPCPX(post-I)group) to the end of experiment. The isoflurane groups had alower end-diastolic pressure than the control groups (P<0.05).Developed pressure recovered to 77, 76, and 82% in Iso, Iso+DPCPX(pre-I)and Iso+DPCPX(post-I) groups, respectively (P<0.05 comparedwith control groups). LV+dp/dt_max recovered to 53, 86, 81, 84,and 60% of pre-ischaemic values in Cont, Iso, Iso+DPCPX(pre-I),Iso+DPCPX(post-I), and DPCPX groups. LV-dp/dt_min recovered to55, 84, 83, 81, and 62%, respectively. Both LV+dp/dt_max andLV-dp/dt_min were significantly different (P<0.05) betweencontrol and isoflurane groups during reperfusion. There wereno significant differences among the isoflurane groups. Ourdata show that isoflurane enhances the post-ischaemic functionalrecovery of isolated rat heart and that block of A₁ receptorsdoes not abolish the beneficial effects of isoflurane. We concludethat A₁receptors are not involved in isoflurane-induced myocardialprotection in the isolated rat heart. Br J Anaesth 2001; 87: 258–65