Remote and local effects of ischemic preconditioning on vascular function: a case for cumulative benefit

Abstract

Brief, repeated cycles of limb ischaemia and reperfusion (ischaemic preconditioning; IPC) can protect against vascular insult. Few papers have considered the effect of IPC on resting vascular function, and no single study has simultaneously considered the local (trained arm) and remote (untrained arm) effect of a single session of IPC, and following repeated sessions. We determined macrovascular (allometrically-scaled flow mediated dilation; FMD) and microvascular (cutaneous vascular conductance; CVC) function in healthy adults before, immediately post, 20 min post and 24 h post a single session of IPC (4 x 5 min of single arm ischaemia). These outcomes also were re-measured 24 h after 6 IPC sessions, performed over 2 weeks. FMD and CVC increased in both arms 20 min post (FMD mean difference (MD) 1.1%, P<0.001; CVC MD 0.08 AU, P=0.004) but not 24 hour post (FMD MD -0.2%, P=0.459; CVC MD -0.02 AU, P=0.526) a single session of IPC, with no differences between trained and untrained arms. Whilst FMD did not increase 24 h after one IPC session, it was elevated in both arms 24 h after the sixth session (MD 1.2%, P=0.009). CVC was not altered in either arm 24 h after the last IPC session. These data indicate that the local and remote effect of IPC on vascular health may be equivalent, and that the benefits to FMD may be greater with sustained training compared to a single IPC exposure.