ABSTRACT
Objective To compare the regulating effect of electrically stimulating different parts of the auri-cle on the cardiac vagus nerve in rats, and to explore the basic neural mechanism. Methods The tragus, concha auriculae and helix of 24 male Sprague-Dawley rats were stimulated at different intensities ( 0-16 mA) and with differ-ent durations ( 0-15 min) and any changes in the heart rate were observed. One week later, the rats were randomized into a tragus injection group, a concha auriculae injection group, a helix injection group and a control group, each of 6. The rats of the first three groups were injected with 2 μL of cholera toxin subunit B conjugate AF555 ( CTB-AF555) at the right auricle, while the control group was injected with the same amount of aseptic phosphate-buffered saline at the right tragus. Five days later, all of the rats were sacrificed and their right superior and inferior ganglia and the whole bulbus medullae were resected to observe the fluorescent labeling sites. Results The rats'heart rate declined with longer and more intense stimulation of the tragus or concha auriculae, but not with stimulation of the he-lix. With stimulation of the same duration, a significant decrease was observed in the heart rate when the tragus and concha auriculae were stimulated at 10, 12, 14 or 16 mA compared with when the helix was stimulated at the same intensities. The heart rate when the concha auriculae was stimulated at 12 mA was significantly slower than when the tragus was stimulated at the same intensity. At identical stimulus intensities, the heart rate slowed significantly more when the tragus was stimulated for 6 to 15 minutes and the concha auriculae for 4 to 15 minutes compared with stimu-lating the helix for the same length of time. And compared with stimulating the tragus for 6 to 10 minutes, the heart rate decreased significantly more when the concha auriculae was stimulated for the same length of time. All of the rats in the tragus and concha auriculae injection groups displayed nerve tracer in their superior and inferior ganglia. In the tragus injection group, CTB-AF555 was observed in the nucleus tractus solitarius ( NTS) of 3 of the 6 rats. In the concha auriculae injection group it was observed in 4 of the 6. In the helix injection group, CTB-AF555 was observed in the nucleus of the spinal tract in 5 of the 6 rats, but no nerve tracer was found in their superior or inferior ganglia or in the NTS. Conclusion Electrical stimulation of the tragus and concha auriculae can regulate the functioning of the cardiac vagus nerve, but stimulating the helix cannot. This is partly because the nerve signals in tragus or concha auriculae stimulation and the cardiac sensory nerve signal are integrated in the inferior ganglion and then analyzed and processed in the bulbar center to monitor the heart.
ABSTRACT
Objective:To compare the ability between bone marrow-derived mesenchymal stem cells (MSCs) (BM-MSCs) and adipose-derived MSCs (AD-MSCs) or umbilical cord-derived MSCs (UC-MSCs) on promotion of vessels formation and vessds stabilization relevant to the functions of EPCs.Methods:In vitro,co-culture blood vessel test was performed to compare the angiogenic ability between BM-MSCs,AD-MSCs or UC-MSCs.In vivo,angiogenic assay dependent on basement membrane matrix Matrigel and immunohistochemistry were performed to compare the ability of vessels formation functions between BM-MSCs and AD-MSCs or UC-MSCs.Results:The lengths and dots of vascular structures formed by EPCs on AD-MSCs layer are greater than those by EPCs on BM-MSCs layer and UC-MSCs layer in angiogenic assay in vitro.The stability of the capillary-like structures formed by EPCs with AD-MSCs on Matrigel was more stable than that by the BM-MSCs,UC-MSCs or EPCs.AD-MSCs and EPCs could form abundant functional vessels with blood perfusion in Matrigelin vivo;UC-MSCs and EPCs could form a few functional vessels with blood perfusion in Matrigelin vivo;BM-MSCs and EPCs could form broken vessels with hemocytes leakage in Matrigel in vivo.Conclusion:AD-MSCs have the stronger ability to promote the angiogenesis and stabilize the vessels compared with BM-MSCs or UC-MSCs ex vivo and in vivo.