Mechanically Induced Vasospasm-Evaluation of Spasmolytic Efficacy of 10 Pharmaceutical Agents Using Laser Speckle Contrast Imaging

Vasodilating Effects of Antispasmodic Agents and Their Cytotoxicity in Vascular Smooth Muscle Cells and Endothelial Cells-Potential Application in Microsurgery

This study aimed to elucidate the vasodilatory effects and cytotoxicity of various vasodilators used as antispasmodic agents during microsurgical anastomosis. Rat smooth muscle cells (RSMCs) and human coronary artery endothelial cells (HCAECs) were used to investigate the physiological concentrations and cytotoxicity of various vasodilators (lidocaine, papaverine, nitroglycerin, phentolamine, and orciprenaline). Using a wire myograph system, we determined the vasodilatory effects of each drug in rat abdominal aortic sections at the concentration resulting in maximal vasodilation as well as at the surrounding concentrations 10 min after administration. Maximal vasodilation effect 10 min after administration was achieved at the following concentrations: lidocaine, 35 mM; papaverine, 0.18 mM; nitroglycerin, 0.022 mM; phentolamine, 0.11 mM; olprinone, 0.004 mM. The IC₅₀ for lidocaine, papaverine, and nitroglycerin was measured in rat abdominal aortic sections, as well as in RSMCs after 30 min and in HCAECs after 10 min. Phentolamine and olprinone showed no cytotoxicity towards RSMCs or HCAECs. The concentrations of the various drugs required to achieve vasodilation were lower than the reported clinical concentrations. Lidocaine, papaverine, and nitroglycerin showed cytotoxicity, even at lower concentrations than those reported clinically. Phentolamine and olprinone show antispasmodic effects without cytotoxicity, making them useful candidates for local administration as antispasmodics.

Segmental branches emanating from saphenous nerve morphing into sympathetic trunks for innervation of saphenous artery and its clinical implication for arterial sympathectomy

Sympathectomy of arteries has been adopted for the treatment of peripheral arterial disease and Raynaud's disease. However, the exact route for sympathetic axons to reach peripheral arteries awaits further investigation that could pave the way for development of new surgical strategies. In this study, saphenous neurovascular bundles from 10 neonatal Sprague-Dawley rats first were harvested for whole-mount immunostaining to show sympathetic innervation pattern of the artery. Secondly, 40 Sprague-Dawley male rats weighing 350 to 400 g were assigned to five groups, receiving either sham, perivascular sympathectomy, nerve-artery separation, nerve transection in the saphenous neurovascular bundle, or lumbar sympathectomy surgery that removes the lumbar sympathetic trunks. Immediately after surgery, the arterial perfusion and diameter were measured using laser speckling contrast imaging, and 1 week later the saphenous neurovascular bundles were harvested for immunostaining using antibodies against TH, neuron-specific β-tubulin (Tuj 1), and α-SMA to show the presence or absence of the TH-immuopositive staining in the adventitia. The differences among the five groups were determined using one-way analysis of variance (ANOVA). We found that an average of 2.8 ± 0.8 branches with a diameter of 4.8 ± 1.2 μm derived from the saphenous nerve that morphed into a primary and a secondary sympathetic trunk for innervation of the saphenous artery. Nerve-artery separation, nerve transection, and lumbar sympathectomy could eradicate TH-immunopositive staining of the artery, resulting, respectively, in a 12%, 36%, and 59% increase in diameter (P < .05), and a 52%, 63%, and 201% increase in perfusion compared with sham surgery (P < .01). In contrast, perivascular sympathectomy did not have a significant impact on the TH-immunopositive staining, the diameter, and perfusion of the distal part of the artery (P > .05). We conclude that the sympathetic innervation of an artery derives from segmental branches given off from its accompanying nerve. Nerve-artery disconnection is a theoretic option in sympathectomy of an artery.