Kraske S, Cunningham J T, Hajduczok G, Chapleau M W, Abboud F M, Wachtel R E
Cardiovascular Center, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.
Am J Physiol. 1998 Oct;275(4):H1497-501. doi: 10.1152/ajpheart.1998.275.4.H1497.
Cell-attached patch-clamp experiments were performed on dissociated neurons from nodose ganglia of adult rats. Putative aortic baroreceptor neurons were identified by labeling nerve endings in the adventitia of the aortic arch with the carbocyanine dye DiI. Whereas previous experiments demonstrated the presence of mechanosensitive (MS) whole cell currents, these experiments studied single MS ion channels and examined the influence of culture conditions on their expression. Single MS channels were activated by applying negative pressure through the recording pipette. Channel openings became more frequent as the negative pressure was increased, with open probability increasing significantly above 30 mmHg. MS channels had a slope conductance of 114 pS and a reversal potential of approximately 0 mV, consistent with a nonspecific cation conductance. Channels were not affected by antagonists of voltage-gated conductances but were blocked by 20 microM gadolinium, a known blocker of MS ion channels. When nodose neurons were cocultured with aortic endothelial cells, but not aortic smooth muscle cells, the percentage of patches exhibiting MS ion channels increased significantly, suggesting that aortic endothelial cells secrete a diffusible factor that increases channel expression.
对成年大鼠结状神经节的解离神经元进行了细胞贴附式膜片钳实验。通过用羰花青染料DiI标记主动脉弓外膜中的神经末梢，鉴定出假定的主动脉压力感受器神经元。尽管先前的实验证明了机械敏感（MS）全细胞电流的存在，但这些实验研究了单个MS离子通道，并研究了培养条件对其表达的影响。通过记录电极施加负压来激活单个MS通道。随着负压增加，通道开放变得更加频繁，当负压超过30 mmHg时，开放概率显著增加。MS通道的斜率电导为114 pS，反转电位约为0 mV，这与非特异性阳离子电导一致。通道不受电压门控电导拮抗剂的影响，但被20 μM钆阻断，钆是一种已知的MS离子通道阻断剂。当结状神经元与主动脉内皮细胞而非主动脉平滑肌细胞共培养时，显示MS离子通道的膜片百分比显著增加，这表明主动脉内皮细胞分泌一种可扩散因子，该因子可增加通道表达。
