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The excitability of aortic denervated vascular smooth muscle is closely related to osmotic pressure changes caused by in-tracellular Ca2+ concentration.The relationship between the excitability and spontaneous contraction of aortic denervated vascular smooth muscle can be known through measurement of membrane current changes in aortic denervated smooth muscle,which helps to reveal the biomechanical characteristics of the aorta,an elastic storage vessel,when Ca2+ concentra-tion in internal environment changes.This study was designed to investigate the effects of changes in Ca2+ concentration in hypoelectrolytic iso-osmotic solution on membrane current changes in aortic denervated smooth musde,and observed the spontaneous contraction of aortic denervated smooth muscle in different loading states.The two ends of relaxed Kunming mouse aortic denervated smooth muscle specimen were infiltrated in the Ringer solution.The membrane current change in aortic denervated smooth muscle under physiological osmotic pressure was observed using a glass microelectrode under the microscope.Ca2+ concentration in the Ringer solution was increased to 30% and membrane current change was observed immediately after osmotic pressure change.When preloads ranged from 0 to 1 g under the iso-osmotic pressure,mem-brane current change was determined and the curves describing the spontaneous contraction of aortic denervated smooth muscle specimen were plotted.Under the iso-osmotic condition,the membrane current of relaxed aortic denervated smooth muscle significantly increased when Ca2+ concentration increased to 30% and preload increased to 1 g.Before increase in Ca2+ concentration,the spontaneous contraction amplitude of aortic denervated smooth muscle increased and after Ca2+ concentration adjustment,the frequency and amplitude of spontaneous contractiongreatly were increased.Pre-treatment with calcium channel blocker,0.05% nitrendipine,significantly attenuated membrane current and the spontaneous contrac-tion amplitude of aortic denervated smooth muscle,suggesting that the membrane potential and spontaneous contraction of aortic denervated smooth muscle are led by calcium ions.Taken together,increases in extracellular Ca2+ concentration increased the excitability of aortic denervated vascular smooth muscle and led to generation of great spontaneous contrac-tion of aortic denervated smooth muscle,which effectively improved the compliance of aortic denervated smooth muscle.Calcium channel blockers inhibited Ca2+-mediated transmembrane current,decreased myogenic spontaneous contraction,increased the negative effects of muscle stiffness on improving the function of elastic storage vessels.