Blunting of rapid onset vasodilatation and blood flow restriction in arterioles of exercising skeletal muscle with ageing in male mice

摘要: Exercise capacity and skeletal muscle blood flow are diminished with ageing but little is known of underlying changes in microvascular haemodynamics. Further, it not clear how the sympathetic nervous system affects microcirculation or whether sex differences prevail regulation arteriolar diameter response to contractions. In gluteus maximus C57BL/6 mice, we tested hypothesis that would impair ‘rapid onset vasodilatation’ (ROV) distributing arterioles (second-order, 2A) old (20-month) males (OM) females (OF) relative young (3-month) (YM) (YF). Neither resting (∼17 μm) nor maximum (∼30 2A diameters differed between groups. single tetanic contractions at 100 Hz (duration, 100–1000 ms), ROV responses were blunted by half OM OF, YM YF. With no effect YM, blockade α-adrenoreceptors phentolamine (1 restored OM. Topical noradrenaline nm) YF levels seen further suppressed (P 60% < 0.05) Blood peak was 75–80% vs. 0.05). 30 s rhythmic 2, 4 8 Hz, progressive dilatations did differ age sex. Nevertheless, flows 2- 3-fold greater than We suggest blunts restricts through subtle activation resistance networks.