ABSTRACT
Sarcolipin (SLN) is a 3 kD membrane protein found in sarcoplasmic reticulum (SR). It has 31 amino acid residues; SLN and phopholamban (PLB) are belong to the same protein family, so they have similar physiological functions. SLN inhibits sarcoplasmic reticulum Ca(2+) ATPase (SERCA) activity and reduces its affinity of Ca(2+), resulting in dysfunction of myocardial contraction and heart failure. However, much remains to be elucidated. SLN independently or in conjunction with PLB affects SERCA activity, imbalancing intracellular calcium homeostasis, and reducing myocardial contractivity; these effects promote the development of heart failure.
Subject(s)
Heart Failure/physiopathology , Muscle Proteins/physiology , Myocardial Contraction/physiology , Proteolipids/physiology , Sarcoplasmic Reticulum Calcium-Transporting ATPases/antagonists & inhibitors , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Animals , Calcium-Binding Proteins/physiology , Humans , Muscle Proteins/metabolism , Proteolipids/metabolism , Sarcoplasmic Reticulum/metabolismABSTRACT
Functional Electrical Stimulation (FES) is a technology to generate neural activity in an artificial way to activate muscles. However, as reported by some researchers, the human responses to FES are likely to be affected by several factors, such as spasticity, muscle fatigue, nerve habituation and so forth. Consequently, the function restoration by FES is neither durable, nor stable. In order to realize long-term and stable FES assistance, this study investigated whether and why an Auxiliary Stimulation (AS) to the Gastrocnemius, with current frequency ranged from 2000 to 6000 Hz, could alleviate the symptom of spasticity and muscle fatigue caused by the stimulation to the Tibialis Anterior. We have developed a portable auxiliary stimulator, and performed experiments to verify its effectiveness. The results showed that our approach enabled comparatively stable and durable function restoration assistance. Moreover, for understanding underlying neuromuscular processes elicited by the AS and its qualitative nature, this study also measured the Hoffmann-reflex (H-reflex) in soleus muscle before and after the AS, to interpret the effect of the Auxiliary Stimulation.
Subject(s)
Evoked Potentials, Motor/physiology , Muscle, Skeletal/innervation , Recovery of Function/physiology , Adult , Female , Humans , Male , Outcome Assessment, Health CareABSTRACT
OBJECTIVE: To investigate the effects of Leonurus japonicas on myocardial remodeling induced by isoproterenol (ISO) in rats. METHODS: The model of rat myocardial remodeling was established by subcutaneous injection of ISO (20,10 and 5 mg/kg for 3 days, subsequently 3 mg/kg for 7 days). Rats were randomly divided into five groups: Control, ISO, ISO + enalapril, ISO + Leonurus 8 g/ kg and ISO + Leonurus 16 g/kg. Recorded the values of LVSP, LVEDP, +/- dp/dt (max), cardiac output ( CO). Weighed the body weight (BW), heart weight (HW) and left ventricular weight (LVW) of rats to calculate the values of HW/BW and LVW/BW. The hydroxyproline contents were investigated by spectrophotometric measurement. The contents of type I collagen and type III collagen and ratio of I/III collagen were assessed by immunohistochemical stain. RESULTS: Leonurus (16 g/kg x day(-1)) could increased the value of LVSP, + dp/dt(max), CO (P < 0.05). Leonurus (8 g/kg) could increased the value of -dp/dt(max), decreased the ratios of HW/BW and LVW/BW (P < 0.05), the contents of hydroxyproline, type I collagen, type III collagen and the ratios of I/III collagen (P < 0.05). CONCLUSIONS: Leonurus at a dosage of 16 g/kg may improve the systolic function; Leonurus at a dosage of 8 g/kg may improve the diastolic function, down-regulate the expression of collagen and normalize the ratio of I/III collagen.
Subject(s)
Leonurus/chemistry , Myocardium/pathology , Plant Extracts/pharmacology , Ventricular Function, Left/drug effects , Ventricular Remodeling/drug effects , Animals , Antioxidants/isolation & purification , Antioxidants/pharmacology , Collagen/metabolism , Disease Models, Animal , Hemodynamics/drug effects , Hydroxyproline/metabolism , Immunohistochemistry , Isoproterenol/administration & dosage , Male , Myocardium/metabolism , Organ Size/drug effects , Plant Extracts/isolation & purification , Plants, Medicinal/chemistry , Random Allocation , Rats , Rats, Sprague-Dawley , Ventricular Pressure/drug effectsABSTRACT
As reported by some researchers, human responses to Functional Electrical Stimulation (FES) are likely to be affected by several factors, such as spasticity, muscle fatigue, nerve habituation and so forth. In our previous study, it has been shown that, an sub-threshold Auxiliary Stimulation (AS) to the Gastrocnemius, with current frequency ranged from 2000 to 6000Hz, could alleviate the symptom of spasticity and muscle fatigue caused by the stimulation to the Tibialis Anterior, enable comparatively stable and durable function restoration assistance. To understand the underlying neuromuscular processes elicited by the auxiliary electrical stimulation and its qualitative natures, we have measured the Hoffmann-reflex (H-reflex) in human soleus muscle before and after the AS in this study,, and proposed a mathematical model which takes into consideration not only the efferent but also afferent neural pathways, to interpret the effectiveness of the AS. Based on the results from the experiment it can be noted that: H(max)/M(max) became lower after AS, AS could reduce the excessive excitability of Alpha MNs. The mathematical model of pre-synaptic inhibition could help us to understand the underlying neuromuscular processes elicited by electrical stimulation and its qualitative nature, and used it to predict the states of spinal cord more easily, quickly, and reasonably in clinic experiment as a medical evaluation method for the paralyzed humans.
