Nerve-Evoked Constriction of Rat Tail Veins Is Potentiated and Venous Diameter Is Reduced after Chronic Spinal Cord Transection

作者：Tripovic Diana; Al Abed Amr; Rummery Nicole M; Johansen Niloufer J; McLachlan Elspeth M; Brock James A^*

来源：Journal of Neurotrauma, 2011, 28(5): 821-829.

DOI：10.1089/neu.2008.0788

• autonomic dysreflexia
• neurovascular transmission
• spinal cord injury
• sympathetic nerve
• vascular reactivity

Despite reduced sympathetic activity below the level of a spinal cord injury (SCI), venoconstriction during autonomic dysreflexia increases venous return to the heart. Here, contractions of isometrically mounted tail veins from rats with spinal transection at T4 performed 8 - 10 weeks earlier are compared with those from sham-operated rats. After SCI, lumen diameter was reduced by similar to 30% and the contractions evoked by electrical stimulation of the perivascular axons were larger than control. This augmentation of neurovascular transmission was not associated with enhanced sensitivity to alpha-adrenoceptor agonists or to adenosine-5'-triphosphate (ATP) although contractions to depolarization with K+ were larger after SCI. The percentage reduction in nerve-evoked contraction after SCI produced by the alpha(1)-adrenoceptor antagonist prazosin (10 nM) was unchanged but that by the alpha(2)-adrenoceptor antagonist rauwolscine (0.1 mu M) was reduced. The relative contribution of P2-purinoceptors to nerve-evoked contractions after alpha-adrenoceptor blockade, revealed by adding suramin (0.1 mM), was unchanged. The greater depolarization-induced contraction and the reduced contribution of alpha(2)-adrenoceptors to nerve-evoked contraction suggest that changes in the venous smooth muscle underlie the potentiation of neurovascular transmission after SCI. Furthermore, the smaller lumen diameter after SCI will increase the pressure that the veins exert on the luminal contents when they are neurally activated.

• 出版日期2011-5