Inhibition of rat prostate smooth muscle contractility by extracts of Costus speciosus(crepe ginger)

Background:This study examined the chemistry and biological effects of Costus speciosus(J.Koenig)Sm.(C.speciosus)which has been traditionally used by Sarawak natives to treat urological disorders for centuries.Methods:This study assesses the efficacy of C.speciosus in treating urological disorders by investigating its effects on the contractility of isolated prostate glands since this is the most effective way to relieve lower urinary tract symptoms that accompany benign prostatic hyperplasia.Plants were collected and extracts of C.speciosus rhizome,root,leaf and stem were made using water at different temperatures.Results:C.speciosus rhizome and root decoction(boiling,about 100℃)combination extract(2 mg/mL)inhibited electrical field stimulation-induced neurogenic contractions of isolated rat prostatic gland by 44±8%(p=0.01,n=4);whereas room temperature(about 20℃)rhizome and root combination extract inhibited electrical field stimulation contractions by 62±8%(p=0.003,n=4).C.speciosus rhizome(p=0.0004,n=6),root(p<0.0001,n=6)and stem(p=0.0057,n=6)room temperature extracts inhibited electrical field stimulation-induced contractions of rat prostatic smooth muscle but leaf extract did not(p=0.09,n=6).Contractions mediated by exogenous administration of noradrenaline,acetylcholine,adenosine 5’-triphosphate or tyramine were only weakly inhibited by rhizome extract.Fractions of C.speciosus rhizome room temperature extract separated by preparative high-performance liquid chromatography and evaluated by isolated organ bath bioassay revealed that inhibitory activity of the extract was due to highly polar soluble components present in the extract.Conclusion:C.speciosus extracts exert a direct inhibitory effect on prostate tissue which is likely to be therapeutically beneficial in treating lower urinary tract symptoms associated with benign prostatic hyperplasia.

Contractility detection of isolated mouse papillary muscle using myotronic Myostation-Intact device

Background:To understand the relationship between myocardial contractility and ex-ternal stimuli,detecting ex vivo myocardial contractility is necessary.Methods:We elaborated a method for contractility detection of isolated C57 mouse papillary muscle using Myostation-Intact system under different frequencies,volt-ages,and calcium concentrations.Results:The results indicated that the basal contractility of the papillary muscle was 0.27±0.03 mN at 10 V,500-ms pulse duration,and 1 Hz.From 0.1 to 1.0 Hz,con-tractility decreased with an increase in frequency(0.45±0.11-0.10±0.02 mN).The voltage-initiated muscle contractility varied from 3 to 6 V,and the contractility gradu-ally increased as the voltage increased from 6 to 10 V(0.14±0.02-0.28±0.03 mN).Moreover,the muscle contractility increased when the calcium concentration was increased from 1.5 to 3 mM(0.45±0.17-1.11±0.05 mN);however,the contractility stopped increasing even when the concentration was increased to 7.5 mM(1.02±0.23 mN).Conclusions:Our method guaranteed the survivability of papillary muscle ex vivo and provided instructions for Myostation-Intact users for isolated muscle contractility investigations.

Effects of Electric Stimulations Applied During Absolute Refractory Period on Ventricular Muscle from Rabbits

Objectives To investigate the influences of electric signals applied during absolute refractory period (ARP) on the contractility of isolated papillary muscle from rabbits. Methods Papillary muscle was exercised from the right ventricle and was paced at 1 Hz. Biphasic square wave current pulse was delivered during the absolute refractory period (called CCM) in isolated, superfused, isometrically contractility rabbit papillary muscle. The peak tension (PT) of papillary muscle, as well as maximum positive tension change ( + dT/dtmax), were observed. Results Compared with the baseline, both PT and + dT/dtmax significantly increased during CCM stimulation by 18.2% and 21.4% respectively (P < 0. 05) . In addition, PT increased significantly with one or two beats following CCM signal application and reached a. new steady state level after a few beats. Once the CCM signals were turned off, the PT returned to the approximately baseline level ( P < 0. 05). Moreover, the effect of CCM on PT was dose - response to voltage. The obvious effect was at higher voltage. No effect was observed at lower voltage. Conclusions Electric signals delivered during the absolute refractory period can rapidly enhance the contractility of myocardium, which suggests that CCM signal is a novel potent method for contractility modulation.

THE IMPROVEMENT OF INFARCTED MYOCARDIAL CONTRACTILE FORCE AFTER AUTOLOGOUS SKELETAL MUSCLE SATELLITE CELL IMPLANTATION

Objective To study the improvement of infarcted myocardial contractile force after autologous skeletal muscle satellite cell implantation via intracoronary arterial perfusion. Methods Skeletal muscle cells were harvested from gluteus max of adult mongrel dogs and the cells were cultured and expanded before being labeled with DAPI (4’, 6-diamidino-2-phenylindone). The labeled cells were then implanted into the acute myocardial infarct site via the ligated left anterior descending (LAD) coronary artery. Specimens were taken at 2nd, 4th, 8th week after myoblast implantation for histologic and contractile force evaluation, respectively. Results The satellite cells with fluorescence had been observed in the infarct site and also in papi- llary muscle with consistent oriented direction of host myocardium. A portion of the implanted cells had differen- tiated into muscle fibers. Two weeks after implantation, the myocardial contractile force showed no significant difference between the cell implant group and control group. At 4 and 8 week, the contractile force in the cell implant group was better than that in control group. Conclusion The skeletal muscle satellite cells, implanted into infarct myocardium by intracoronary arterial perfusion, could disseminate through the entire infarcted zone with myocardial regeneration and improve the contractile function of the infarcted myocardium.

The Effects of Ground and Treadmill Running on Energy Metabolism and Muscle Contractile Properties:A Randomized Cross-Over Study

Purpose This study aimed to compare the effects of ground and treadmill running on energy metabolism and muscle con-tractile properties,providing a basis for the general public to choose running venues.Methods Ten male college students(age,20.10±1.53 years;height,176.20±5.49 cm;weight,72.14±8.25 kg;body fat percent,12.41%±4.65%)were recruited in this study.Energy expenditure(EE)was measured using the accelerometer(GT9X)combined with specific estimation equations.Average heart rate(HR)was measured using a heart rate band(Polar).Muscle contractile properties were assessed by measuring muscle displacement(Dm)and contraction velocity(Vc)using tensiomyography(TMG-S1).Blood glucose(Glu)and lactate(Lac)were measured by portable devices(eB-G and Lactate Scout).The running speed was 9 km/h and the duration was 25 min.Two-way ANOVA(protocol×time)was used to analyze the effect of running protocols on energy metabolism and muscle contractile properties.Results EE of treadmill running was significantly higher than EE of ground running(protocol main effect,P<0.001),and HR of treadmill running was significantly higher than that of ground running in the first testing time(protocol simple effect,P=0.026;protocol×time interaction P=0.043).The decrease in Dm of the rectus femoris after treadmill running was significantly higher than that of ground running(protocol main effect,P=0.009).The interaction of different running protocols and testing times on Lac was significant(P=0.025),but all results of the simple effects analysis were not statisti-cally significant(P>0.05).Conclusion Our study found a difference in energy expenditure between treadmill and ground running at 9 km/h with duration of 25 min.In addition,treadmills are more likely to cause a decrease in muscle displacement distance of the rectus femoris measured after exercise than ground running.Future studies are needed to further investigate whether the differences are induced by internal metabolism or the environmental conditions of running.