Transient lower esophageal sphincter (LES) relaxation (TLESR) is defined as LES relaxation without a swallow. TLESRs are observed in both of the normal individuals and the patients with gastroesophageal reflux disorder (GERD). However, TLESR is widely considered as the major mechanism of the GERD. The new equipments such as high resolution manometry and impedance pH study is helped to understand of TLESR and the related esophageal motor activities. The strong longitudinal muscle contraction was observed during development of TLESR. Most of TLESRs are terminated by TLESR related motor events such as primary peristalsis and secondary contractions. The majority of TLESRs are associated with gastroesophageal reflux. Upper esophageal sphincter (UES) contraction is mainly associated with liquid reflux during recumbent position and UES relaxation predominantly related with air reflux during upright position. The frequency of TLESR in GERD patients seems to be not different compared to normal individuals, but the refluxate of GERD patients tend to be more acidic during TLESR.
Esophageal Sphincter, Lower/*physiology ; Esophagogastric Junction/physiology ; Esophagus/*physiology ; Gastroesophageal Reflux/*physiopathology ; Humans ; Muscle Relaxation/physiology

OBJECTIVEThe aim of this study was to establish the average of superfacial masseter muscle of young females with normal occlusion, and further supply a clue for dentists to evaluate the muscle function of patients with malocclusion.

METHODSTotally 31 young females were investigated in this study, whose mean age was 21 years and 4 months old. Ultrasound technique was applied to obtain the ultrasound parameters of images, including area, width, mean thickness, maximal thickness of the cross-section and the length of the vertical-section of the masseter muscle under relaxing, maximal clenching and maximal protruding condition. The data were analyzed using ANOVA analysis.

RESULTSThe mean value and standard deviation of every parameter were figured out and it was found that there was a significant difference between relaxing and maximal clenching as well as maximal protruding.

CONCLUSIONThe result indicates that ultrasonic technique is an effective method for describing superfacial masseter muscle morphology and diagnosing its function.

Adult ; Dental Occlusion ; Female ; Humans ; Mandible ; physiology ; Masseter Muscle ; anatomy & histology ; diagnostic imaging ; Muscle Contraction ; Muscle Relaxation ; Ultrasonography

It is known that penile erection is mediated primarily through the release of a nonadrenergic noncholinergic (NANC) neurotransmitter which has been recently identified as nitric oxide (NO). To evaluate whether the endothelium is involved in neurally mediated relaxation in corpus cavernosum, we determined electrical field stimulation (EFS) induced relaxation in both the presence and absence of endothelium, and we tested the effect of an inhibitor of NO synthase, NG-nitro-L-arginine (NOARG), in the absence of endothelium to examine if de-endothelialized tissue can still generate NO. Isolated corpus cavernosal strips from New Zealand White rabbits were used for isometric tension study using organ chambers. The endothelium was removed through denuding tissue. After the tissue was contracted with norepinephrine, EFS was performed at frequencies of 5, 15 and 40 Hz in the presence of guanethidine and atropine to evaluate NANC-selective nerural relaxation. The relaxation induced by EFS was observed after preincubation with NOARG(10(-4) M) for 30 minutes. L-arginine (10(-3) M) was then added for 30 minutes in the presence of NOARG before a second set of EFS studies were performed. Following norepinephrine precontraction, EFS relaxed corporal strips in both the intact and de-endothelialized strips. However, deendothelialization significantly impaired EFS induced relaxation (p< 0.05). NOARG attenuated relaxation induced by EFS and the addition of L-arginine reversed the inhibitory effect of NOARG in the strips with endothelium. In the strips without endothelium, NOARG still inhibited EFS induced relaxation. This relaxation was reversed by the addition of L-arginine.
Animal ; Endothelium/physiology ; Male ; Muscle Relaxation ; Neurons/metabolism ; Nitric Oxide/*physiology ; *Penile Erection ; Penis/innervation/*physiology ; Rabbits

AIMTo evaluate the relaxant effect of verapamil on human corpus cavernosum in vitro and to assess the drug's potential as a treatment for erectile dysfunction (ED).

METHODSPreparations of the human corpus cavernosum were obtained from recently deceased young men who had had normal erectile function. The isometric tension and detailed curves were recorded when contractions induced by 10 micromol/L phenylephrine were reduced by different doses of verapamil or the vehicle control (sterile water). The tension of human corpus cavernosum preparations are described as a percentage of their top tension before adding verapamil or the vehicle. ANOVA and least significant difference tests were used for statistical analysis.

RESULTSDoses of 1 micromol/L, 10 micromol/L and 100 micromol/L verapamil resulted in relaxation of (35.28+/-7.96)%, (55.91+/-6.41)%, (85.68+/-4.16)% after 30 min, respectively. The vehicle control at the same time point produced relaxation of (-0.06+/-10.57)% (P<0.05).

CONCLUSIONVerapamil is significantly effective in relaxing normal human corpus cavernous smooth muscle induced by phenylephrine in vitro and the relaxant effect depends on the concentration of verapamil.

Adult ; Humans ; In Vitro Techniques ; Male ; Muscle Relaxation ; drug effects ; Muscle, Smooth, Vascular ; drug effects ; physiology ; Penis ; drug effects ; physiology ; Verapamil ; pharmacology

There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca(2+)-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting supported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca(2+)-pumping activity.
Animals ; Bufonidae ; physiology ; Electric Stimulation ; Electrophysiology ; In Vitro Techniques ; Indoles ; pharmacology ; Kinetics ; Models, Animal ; Models, Biological ; Muscle Relaxation ; drug effects ; physiology ; Muscle Tonus ; drug effects

The changes in excitability and autorhthmicity of bladder detrusor in experimental non-insulin dependent diabetes mellitus (NIDDM) rats were observed. Sixty-nine NIDDM rats as NIDDM group and 69 normal rats as control group were enrolled into this experimental study. At 6th, 10th, 14th, 18th, 22nd and 26th week after the rats were injected last time, the changes in the excitability and autorhthmicity of detrusor strips in vitro were observed. The results showed that the threshold of the tension which made the detrusor strips contract was significantly higher in NIDDM group (0.716 +/- 0.325 g) than in control group (0.323 +/- 0.177 g) (F = 59.63, P < 0.001). At different stages, the threshold of the tension resulting the contract of the detrusor strips in NIDDM group was also higher than in control group. At 18th week after STZ injection, the frequency of spontaneous contract of the detrusor strips in NIDDM was significantly higher than in control group (P < 0.05), whereas at 22nd week, that in NIDDM group was significantly lower than in control group (P < 0.05). It was concluded that the decreased excitability of the bladder detrusor was the earliest and most obvious changes in bladder function in diabetes rats and the autorhthmicity had also changed at the early stage of diabetic bladder.
Diabetes Mellitus, Experimental/*physiopathology ; Diabetes Mellitus, Type 2/physiopathology ; Muscle Contraction/physiology ; Muscle Relaxation/physiology ; Rats, Wistar ; Urinary Bladder/*physiopathology ; Urinary Bladder Diseases/etiology ; Urinary Bladder Diseases/*physiopathology

Hexafluorenium has not been popular in clinical anesthesia due to the occurrence of bronchospasm, cardiac arrest, arrhythmias and histamine release reported from its use since it was introduced in 1954. The authors were primarily interested in studying this drug because it has fascinating dual effects of a weak nondepolarizing action at the myoneural junction and a marked antipseudocholinesterase activity. Forty cases were studied in two different groups. In the 1st group of 20 patients, hexafluorenium, 0. 4mg/kg, was given for intubation. In the 2nd group of 20 patients, hexafluorenium followed by succinylcholine was given after an intubsting dose of succinylcholine had worn off. As a result of this study, we can summarize as follows: 1) This combination of hexafluorenium and succinylcholine provides good relaxation for abdominal surgery. 2) Duration of action of succinylcholine varied, ranging from 30 to 40 minutes. 3) In the 1st group, most of the 20 patients complained of discomfort:, with nausea and oral secretion, but muscular fasciculation elicited by succinylcholine injection was not observed. 4) In the 2nd group, untoward effects, such as nausea and oral secretion, were not observed but it was cumbersome to calculate adequate dose of the drugs in anesthesia practice. 5) No bronchospasm or cardiovascular effects were noted except for one suspected case. 6) It would be acceptable to use this combination of drugs when used with caution and also it is worthwhile to study to understand the physiology of muscle relaxation, because it has a peculiar dual action of muscle relaxation.
Anesthesia ; Arrhythmias, Cardiac ; Bronchial Spasm ; Fasciculation ; Heart Arrest ; Histamine Release ; Humans ; Intubation ; Muscle Relaxation ; Nausea ; Neuromuscular Agents* ; Neuromuscular Junction ; Physiology ; Relaxation ; Succinylcholine*

Acetylcholine ; metabolism ; physiology ; Animals ; Cholinergic Agonists ; pharmacology ; Male ; Muscle Contraction ; drug effects ; physiology ; Muscle Relaxation ; drug effects ; physiology ; Muscle, Smooth ; drug effects ; pathology ; physiopathology ; Rabbits ; Random Allocation ; Receptors, Cholinergic ; physiology ; Synaptic Transmission ; drug effects ; Urinary Bladder ; drug effects ; innervation ; physiopathology

OBJECTIVETo observe the effect of β₃adrenoceptors (β₃-AR) activation on rat thoracic aorta smooth muscle contractility and the possible related mechanism.

METHODSThe endothelium removed thoracic aorta was pre-contracted with 30 mmol/L KCl physiological saline solution (PSS). Then the tension of the thoracic aorta was recorded in presence of BRL37344 (BRL) to determine the action of β₃-AR. The tension of the thoracic aorta was also recorded in the presence of Propranolol (PRA), SR59230A (SR), L-NNA, H-89 and Iberiotoxin (IBTX) respectively to reveal the underling mechanism of β₃-AR activation on rat vascular smooth muscle. Immunohistochemistry was adopted to confirm the existence and the distribution of β₃-AR in rat thoracic aorta.

RESULTSThe results showed that: (1) The thoracic aorta was relaxed by β₃-AR activation, with a relaxation percentage of (10.59 ± 0.79). (2) β₃-AR was expressed in both endothelial and smooth muscle layer in thoracic aorta sections of rats. (3) PRA did not block the effect of BRL on the thoracic aorta. The relaxation actions of BRL could be antagonized by pre-incubating the thoracic aorta with SR. (4) L-NNA (a NOS inhibitor) and H-89 (a PKA inhibitor) reversed the relaxation effect of BRL on vascular smooth muscle. (5) The effect of BRL was decreased after application of Ibriotoxin (IBTX), a large conductance calcium dependent potassium channel blocker.

CONCLUSIONThe results confirmed that activation of β₃-AR led to relaxation of thoracic aorta smooth muscle. The relaxation action of β₃-AR on smooth muscle of rat thoracic aorta was related to activation of NOS and PKA signaling pathway. Large conductance Ca²⁺-K⁺ channels were involved in the relaxation action of β₃-AR activation on rat thoracic aorta smooth muscle.

Animals ; Aorta, Thoracic ; physiology ; In Vitro Techniques ; Isoquinolines ; Large-Conductance Calcium-Activated Potassium Channels ; physiology ; Muscle Contraction ; Muscle Relaxation ; Muscle, Smooth, Vascular ; physiology ; Nitroarginine ; Peptides ; Propanolamines ; Propranolol ; Rats ; Receptors, Adrenergic, beta-3 ; physiology ; Signal Transduction ; Sulfonamides

Ethanol has various effects on male sexual activity under the influence of direct and indirect, in acute and chronic alcohol ingestion. However, whether acetaldehyde, a principal metabolite of ethanol, may affect penile erection directly has still not been elucidated. This present study was, therefore, designed to clarify the pharmacologic effects of the acetaldehyde on corpus cavernosal smooth muscle. Corpus cavernosal strips were prepared from rabbit penises. Isometric tension changes of rabbit corpus cavernosal strips to various drugs and electrical field stimulation (EFS) in an organ chamber were recorded with a pressure transducer after active muscle tone had been induced by phenylephrine (10(-5) mol/L). At the concentrations employed, acetaldehyde had no effect on the pH of the bathing medium. Acetaldehyde in each concentration did not significantly affect resting tone of the smooth muscle during 30 min incubation. Acetaldehyde suppressed contractility induced by phenylephrine and KCI at 10(-4) mol/L, and relaxation induced by EFS and bethanechol at 10(-3) mol/L and 10(-4) mol/L respectively, but acetaldehyde enhanced relaxation induced by ATP at high acetaldehyde level. Sodium nitroprusside-induced relaxation was not affected at any employed acetaldehyde concentration. This suggests that increasing the acetaldehyde level may contribute to male erectile dysfunction mainly by the inhibition of nitric oxide formation.
Acetaldehyde/pharmacology* ; Animal ; Bethanechol/pharmacology ; In Vitro ; Male ; Muscle Contraction/drug effects ; Muscle Relaxation/drug effects ; Muscle, Smooth/physiology ; Muscle, Smooth/drug effects* ; Nitroprusside/pharmacology ; Penis/physiology ; Penis/drug effects* ; Phenylephrine/pharmacology ; Potassium Chloride/pharmacology ; Rabbits