Large artery stiffness increases with local neurogenic blockade in rats

Whilst the functional role of neurogenic control of peripheral blood vessels is well established, the presence of neurogenic terminals in the large arteries has not been linked with changes in large artery stiffness. The aim of this study was to elucidate any change in rat aortic stiffness, through measurement of pulse wave velocity (PWV), as a result of local neurogenic blockade. Methods. Male Sprague-Dawley rats (n7, aged 12–14weeks) were anaesthetised and two 1.3F, high fidelity pressure sensors introduced into the proximal and distal ends of the abdominal aorta for measurement of PWV. Increasing doses (1ug/ml, 10ug/ml & 100ug/ml) of an alpha-adrenergic antagonist (phentolamine) were used to locally chemically denervate the abdominal aorta via bathing through a ventrally exposed cavity. Mean arterial pressure was raised and lowered using intravenously injected phenylephrine and sodium nitroprusside respectively. PWV was measured across the full physiological arterial pressure range, and during the different levels of local neurogenic blockade. Results. The increasing concentrations of phentolamine caused aortic PWV to increase concordantly. Neurogenic blockade caused a significant change in PWV at arterial pressures above 110mmHg, with PWV increasing from 5% (1ug/ml phentolamine) to 10% (10ug/ml phentolamine) compared to control values (P0.05). The response was more pronounced at aortic pressures above 130 mmHg, with 10ug/ml phentolamine resulting in a 12.5% increase in PWV compared to control (P0.01). Conclusions. These results show that local neurogenic blockade in large arteries can significantly increase local arterial stiffness. This demonstrates that neurogenic input into large arteries results in functional physiological changes that could impact on blood pressure regulation.