Repeated exposures to moderately increased intravascular pressure increases stiffness in human arteries and arterioles

OBJECTIVE: The aim was to investigate whether repeated exposures to moderate pressure elevations in the blood vessels of the arms (pressure training) affect pressure distension in arteries/arterioles of healthy individuals. METHODS: Pressure training and vascular pressure-distension determinations were conducted with the participant (n = 11) seated in a pressure chamber with one arm slipped through a hole in the chamber door. Intravascular pressure was increased by elevating chamber pressure. Before pressure training, one arm was investigated (control arm) during stepwise increases in chamber pressure to 180 mmHg. Diameter and flow were measured in the brachial artery using ultrasonography/Doppler techniques. Thereafter, the contralateral arm underwent pressure training consisting of fifteen 40-min sessions during 5 weeks; local intravascular pressures were elevated by 65-105 mmHg during the sessions. After pressure training, pressure-distension relationships were examined in both the trained arm and the control arm. RESULTS: Pressure training reduced (P < 0.01) arterial pressure distension by 46 ± 18%. Likewise, the pressure-induced increase in arterial flow was less after (350 ± 249%) than before (685 ± 216%) pressure training. The pressure training-induced reductions in arterial/arteriolar pressure distension were reversed 5 weeks after pressure training. CONCLUSION: Thus, the in-vivo wall stiffness in arteries and arterioles increases markedly in response to intermittent, moderate increments of transmural pressure during 5 weeks. The findings are compatible with the notion that local load serves as 'a prime mover' in the development of vascular changes in hypertension.