Real-time measurement of cell contractile force during activation of human hepatic stellate cell line LX-2 / 生物医学工程学杂志

The contractile force of hepatic stellate cells plays a very important role in liver damage, hepatitis and fibrosis. In this paper, a method based on polydimethylsiloxane (PDMS) thin micropillar arrays is proposed to measure the contractile force of human hepatic stellate cell line LX-2, which enables dynamic measurement of the subcellular distribution of force magnitude and direction. First, thin micropillar arrays on glass bottom dish were fabricated using two-step casting process in order to meet the working distance requirement of 100× objective lens. After hydrophilic treatment and protein imprint, cells were seeded on the micropillar arrays. LX-2 cells, which were quiesced by growth in serum-free medium, were activated by adding fetal bovine serum (FBS). The deflections of the micropillars were achieved by image processing technique, and then the contractile force of cells exerted on the micropillars was calculated according to mechanical simulation results, and was analyzed under both quiescent and activated conditions. The experimental results show that the average traction force of quiescent cells is about 20 nN, while the contractile force of activated cells increased to 110 nN upon adding FBS. This method can quantify the contractile force of LX-2 cell on subcellular scale in both quiescent and activated states, which may benefit pathology study and drug screen for chronic liver diseases resulted from liver fibrosis.

Mechanisms underlying the contractile responses to doxazosin enantiomers in the rat isolated atrium / 中国药理学通报

Aim To study the mechanisms of inotropic responses to doxazosin enantiomers in the isolated rat atrium.Methods We analyzed the positive inotropic response to (-)doxazosin and the negative inotropic response to (+)doxazosin in the left atrium of rat u-sing receptor-pharmacological technique.Results In the preparation treated with verapamil,the positive in-otropic responses to 3 μmol·L-1 (-)doxazosin were significantly inhibited from the control level (245.7 1 ± 44.29)mg to (172.50 ±43.34)mg,(P<0.05).In the preparation treated with methylene blue,the posi-tive inotropic responses to 3 μmol·L-1 (-)doxazosin were significantly potentiated from the control level (245.7 1 ±44.29 )mg to (303.33 ±45 .90 )mg,(P<0.05 ).In the preparation treated with H-89 ,the positive inotropic responses to 3,10 and 30 μmol · L-1 (-)doxazosin were (338.57 ±96.86 ) mg, (471.43 ±107.61)mg and (520.00 ±103.44)mg, which were significantly (P<0.05 ~0.01)larger than the control levels of (245.71 ±44.29)mg,(314.29 ±90.34)mg and (357.14 ±68.49 )mg.Treatment with phenoxybenzamine,atropine,propranolol or indo-methacin did not significantly affect the responses to doxazosin enantiomers.Conclusion The positive ino-tropic responses to (-)doxazosin in the isolated left a-trium of rat are partially involved in L-type Ca2+chan-nels and intracellular cGMP level.However,α-adre-noceptors,muscarinic receptors,β-adrenoceptors and cyclooxygenases are not related to the responses to doxazosin enantiomers.

EFFECTS OF FUROSEMIDE ON ACTION POTENTIAL AND CONTRACTILE FORCE OF ISOLATED TOAD ATRlAL MYOCARDIUM / 中国药理学通报

Using floating microelectrode, the effects of furosemide on action potential and contractile force were studied in isolated toad atrial myocardium. Furosemide increased the force of contraction of toad right atrial myocardium, amplitude and dV/dtmax of action potential, and prolonged action potential duration at 50% repolari-zation (APD50), but the APD25, APD90 and sinus cycle length ( SCL) were not influenced. The positive intropic effect of furosemide could be blocked by Verapamil. These results indicated that furosemide could promote the Ca++ inward current.

Effects of matrine on action potentials and contractile force in guinea pig papillary muscles / 中国药理学通报

AIM To study the effects of matrine (Ma) on the action potential and contractile force in guinea pig papillary muscles. METHODS Conventional microelectrode technique was used to record the fast action potentials (FAP) and slow action potentials (SAP) induced by histamine and BaCl_2 of guinea pig papillary muscles. RESULTS Ma 10,25,50 ?mol?L -1 dose-dependently prolonged the action potential duration at 50%, 90% repolarization (APD_ 50 , APD_ 90 ) and effective refractory period (ERP) of FAP, and lengthened the APD_ 50 , APD_ 90 of SAP induced by histamine and BaCl_2 when perfused with KCl 25 mmol?L -1 Tyrode's solution. The maximal upstroke velocity (V_ max ) of FAP, SAP and contractile force (Fc) were not affected by matrine 10,25,50 ?mol?L -1 . CONCLUSION It was suggested that Matrine could block K + channels in the myocardium.-

EFFECTS OF AMRINONE ON CONTRACTION AND ACTION POTEN-TIAL OF ISOLATED PAPILLARY MUSCLES IN GUINEA PIGS / 西安交通大学学报(医学版)

The effects of amrinone on the contraction and action potential of isolated guinca pig papillary muscles were studied with intracellular microelectrodes. When the preparations were exposed to 25 ?mol/L amrinone, their pcak developed tension(DT) was inereased by 65.4%, the maximum rate of force development (dT/dt_(max)) was increased by 50.8% the time to peak developed tension (tPT) was shortened by 15.9%. By raising the concentration of amrinone to 250 ?mol/L, DT and dT/dt_(max) were increased by 98.5% and 91.3%, respectively, and tPT was shortened by 24.7%. Concomitantly, amrinone can prolong the durations of action potential (APD50, APD90)and the effective refractory period (ERP) of the ventricular cells.These results suggest that amrinone (made in China) possesses the obvious positive inotropic effect.