Effects of gadolinium chloride on basal flowand compression-induced rapid hyperemia in the rabbit masseter muscle

Aim of the present study is to investigate the role of mechano-sensitive channels on basal muscle blood flow and on the compression-induced rapid hyperaemia. to this aim,the mechano-sensitive channel blocker gadolinium (gd3+) is employed,which already proved to reduce the myogenic response in isolated vessels. muscle blood flow (mabf) was recorded from the masseteric artery in 8 urethane-anesthetized rabbits. rapid hyperemic responses were evoked by 1-s lasting compressions of the masseter muscle (mc) delivered before and after close arterial infusion of gd3+ in the masseteric artery. three infusions were performed at 1-h interval,producing estimated plasma concentration (epc) of 0.045,0.45 and 4.5 mm,in the masseteric artery. the amplitude of the hyperaemic response to mc,equal to 195±77% of basal flow in control condition,was reduced by 9.5±19.4% (p=0.18) and 45±28% (p<0.01) while basal mabf increased by 10±3% (p=0.90) and by 68±30% (p<0.01) at epc of 0.045 and 0.45 mm,respectively. at epc of 4.5 mm a strong reduction in both mabf (by 54±13%,p<0.01) and mc response (75±12%,p<0.01) was instead observed. these effects did not depend on time from infusion. at all doses employed gd3+ never affected arterial blood pressure,heart rate and contralateral mabf. while the effects observed at the highest epc likely result from blood vessel occlusion due to gd3+ precipitation,the effects observed at lower concentrations demonstrate that gd3+ affects musculo-vascular function by decreasing both resting vascular tone and responsiveness to mechanical stimuli. the results are compatible with a gd3+-induced blockade of vascular mechano-sensitive channels.