Chinese Journal of Tissue Engineering Research ›› 2016, Vol. 20 ›› Issue (24): 3588-3594.doi: 10.3969/j.issn.2095-4344.2016.24.014

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Preload-induced stress relaxation and membrane current changes in the denervated intact smooth muscle

Ni Zhi-zhan1, Li Jie-yao1, Zhang Pei1, Xia Li1, 2, Ye Si-qi1, 2, Annie Christel Bell1, 2, Fan Shou-yan3, Piao Ling-hua3, Chen Zhi-bin1, Gao Ling-feng2, 3, Wang Yang2, 3   

  1. 1School of Clinical Medicine, Hainan Medical University, Haikou 571102, Hainan Province, China; 2Laboratory of Offshore Medical Physiology, Hainan Medical University, Haikou 571101, Hainan Province, China; 3Department of Medical Physiology, Hainan Medical University, Haikou 571101, Hainan Province, China
  • Online:2016-06-10 Published:2016-06-10
  • Contact: Wang Yang, M.D., Associate professor, Associate researcher, Laboratory of Offshore Medical Physiology, Hainan Medical University, Haikou 571101, Hainan Province, China; Department of Medical Physiology, Hainan Medical University, Haikou 571101, Hainan Province, China
  • About author:Ni Zhi-zhan, Assistant technician, School of Clinical Medicine, Hainan Medical University, Haikou 571102, Hainan Province, China
  • Supported by:

    the Major Scientific Research Project of Hannan Provincial Higher Education Schools in 2013, No. Hjkj2013-33; the Training Program of Innovation and Entrepreneurship for Undergraduates of Hannan Province in 2014, No. 20140111, HYCX2014073

Abstract:

BACKGROUND: Muscle stretch test is a method for testing mechanical properties of denervated muscle under diverse loads.
OBJECTIVE: To observe changes of spontaneous tension wave in myography and membrane electric current in aorta smooth muscle samples under several preload conditions.
METHODS: Denervated intact smooth muscle samples were taken from the Kunming mouse aorta and urinary bladder wall. Smooth muscle samples were fixed on a micro positioning device and the first stretch was induced for a passive tension up to 1 g, this position was determined as the initial length (L0). Intermittently, with increasing sample length from L0 every 5 minutes, the 1st and 10th stretch were recorded as low- (L0+1) and high-preload (L0+10). 3% CaCl2 and 0.05% nitrendipine were dropped on the samples before L0+1 and L0+10 stretch were recorded. Membrane current changes were evaluated by glass microelectrodes and MultiClamp 700B Amplifier and pClamp 10 analyzer software. The membrane current changes after L0+1 and L0+10 were analyzed.
RESULTS AND CONCLUSION: Prolonged stress relaxation phase was shortened with increasing preload in smooth muscle preparations. The stress relaxation phase in smooth muscle samples from urinary bladder wall was shorter than aorta samples. It was revealed that there were compliance differences between two kinds of smooth muscle samples. In aorta samples, myogenic spontaneous contraction amplitude during stress relaxation and membrane current were significantly increased with increasing preload. Increased amplitude and frequency of membrane current in aorta smooth muscle samples under high calcium concentration (3% CaCl2) were inhibited by L-type calcium channel blockade (0.05% nitrendipine). Collectively, increased preload in smooth muscle samples induced a directly decrease of compliance with an enlargement of myogenic spontaneous contraction amplitude. It appeared vital in particular in aorta samples. Membrane current significantly enhanced in spontaneous contraction period suggested the mechanical stretching ionic inward flow involved in this period. Membrane current amplitude was increased by high-preload under elevated calcium conditions; however, this change was suppressed by L-type calcium channel blockade. This study indicates quick stretching influences not only mechanically-gated channels in smooth muscle, but also the activation of L-type calcium channel.

中国组织工程研究杂志出版内容重点:组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松组织工程

Key words: Muscle, Smooth, Denervation, Stress, Mechanical

CLC Number: