Effects of site specific antibody of Na+-Ca2+exchanger on calcium transient in single ventricular myocytes of rats / 中国免疫学杂志

Objective:To investigate the effects of site specific (124 HNFTAGDLGP STIVGSAAFNMF145 ) antibody of Sodium calcium exchanger ( NCX) on calcium transient in single ventricular myocytes of normal adult rats .Methods: Isolated adult rat hearts were perfused using Langendorff method and single ventricular myocytes were then obtained .The ventricular myocytes were incubated with Fuar-2/AM and 2% bovine serum albumin for about 40 min and then,the fluorescence images were recorded when excitation wavelengths were 340 nm and 380 nm using ion imaging system.Fluorescence value F340/F380,length of cell shortening ,time to 90%restore( TR90 ) and calcium sensitivity ( ratio of F340/F380 and cell shortening ) were calculated.Results:The site specific antibody of NCX increased F340/F380 and decreased TR90 in single ventricular myocytes ,but had no more significant effect on calcium sensitivi-ty.Pretreatment with KB-R7943 or Nicardipine could significantly inhibit the TR 90 decrease or F340/F380 increase induced by the anti-body.Pretreating ventricular myocytes with combination of KB-R7943 and Nicardipine ,the antibody had no more significant effects on calcium transient.Conclusion:Site specific ( 124 HNFTAGDLGPSTIVGSAAFNMF145 ) antibody of NCX could increase calcium transient and accelerate the decrease of intracellular calcium during diastole ,which mainly related to its effects of activating L-type Ca2+channel and NCX.

The Influences of G Proteins, Ca2+, and K+ Channels on Electrical Field Stimulation in Cat Esophageal Smooth Muscle

NO released by myenteric neurons controls the off contraction induced by electrical field stimulation (EFS) in distal esophageal smooth muscle, but in the presence of nitric oxide synthase (NOS) inhibitor, L-NAME, contraction by EFS occurs at the same time. The authors investigated the intracellular signaling pathways related with G protein and ionic channel EFS-induced contraction using cat esophageal muscles. EFS-induced contractions were significantly suppressed by tetrodotoxin (1 micrometer) and atropine (1 micrometer). Furthermore, nimodipine inhibited both on and off contractions by EFS in a concentration dependent meaner. The characteristics of 'on' and 'off' contraction and the effects of G-proteins, phospholipase, and K+ channel on EFS-induced contraction in smooth muscle were also investigated. Pertussis toxin (PTX, a Gi inactivator) attenuated both EFS-induced contractions. Cholera toxin (CTX, Gs inactivator) also decreased the amplitudes of EFS-induced off and on contractions. However, phospholipase inhibitors did not affect these contractions. Pinacidil (a K+ channel opener) decreased these contractions, and tetraethylammonium (TEA, K+ Ca channel blocker) increased them. These results suggest that EFS-induced on and off contractions can be mediated by the activations Gi or Gs proteins, and that L-type Ca2+ channel may be activated by G-protein alpha subunits. Furthermore, K+ Ca-channel involve in the depolarization of esophageal smooth muscle. Further studies are required to characterize the physiological regulation of Ca2+ channel and to investigate the effects of other K+ channels on EFS-induced on and off contractions.

Toosendanin Modifies K~+-and Ca~(2+)-Channel Activity and Intracellular Ca~(2+) Concentration / 生物化学与生物物理进展

Usage of the fruit and bark of a Melia-family plant as a digestive tract-parasiticide and agricultural insecticide was recorded about two thousant years ago in ancient China. Toosendanin (TSN), a triterpenoid, is an effectual ingredient extracted from the plant. Studies have demonstrated that TSN selectively affects neurotransmitter release, effectively antagonizes botulism, induces cell differentiation and apoptosis and inhibits proliferation of various human cancer cells, inhibits feeding and dovelopment in insects and modifies K+- and Ca2+-channel activity. The research data to demonstrate that TSN inhibits K+-channel and facilitates L-type Ca2+-channel are summarized, and the mechanism of action of TSN is discussed.

Entery of calcium into ECV304 endothelial cell via CaCa~(2+) activated non-selective cation channel / 中国药理学通报

AIM To investigate the pathways of Ca 2+ entry into ECV304 endothelial cell and the effect of angiotensin Ⅱ(AⅡ) on calcium activated non setective cation channel(CAN). METHODS The cell attachment and whole cell configurations of patch clamp technique were used to record channel activity. RESULTS (1) The single channel conductance is ? o=(12 90?2 11) pS( n =4) for Ca 2+ passing through CAN of ECV304 cell in condition of pipette solution without K + and Na + but composed 120 mmol?L -1 CaCl 2. The channel current amplitude and open time can be enhanced by 1?10 -7 mol?L -1 AⅡ. The enhanced conductance in CAN is ? 1=(22 18?2 29) pS( n =4). The results of whole cell recording are identified with single channel recording. (2) The whole cell configuration was carried out for recording voltage dependent Ca 2+ channel in ECV304 cell. The peak current amplitude was (29 32?3 56) pA( n =4). This current was inhibited to (6 00?3 94) pA( n =4) by nifedipine and activated by BayK8644. CONCLUSIONS (1)Ca 2+ enters ECV304 cell via Ca 2+ activated non selective cation channel and voltage dependent L type calcium channel. (2) AⅡ can significantly enhance the calcium entry via CAN in ECV304 cell.

Effect of 15-KETE on rat isolated pulmonary arterial rings / 中国药理学通报

Aim To investigate the effect of 15-ketoeicosatetraenoic acid(15-KETE)and its mechanism through ion channels on rat isolated pulmonary arterial rings by using organ bath technique.Methods Sixteen healthy Wistar rats weighing 220?20 g were divided into two groups(n=8): normoxia group breathing fresh air(FiO_2=21%) and hypoxia group breathing hypoxic air(FiO_2=10%) in a hypoxic box.Pulmonary arteries(PA)were extracted after 9 d and cut into rings(0.5~1.0 mm in diameter and 3 mm in length) for organ bath experiments.Results(1) With increasing concentration from 0 to10~(-6) mol?L~(-1),15-KETE increased PA rings tension gradually in a dosedependent fashion;(2) 4-aminopyridine(2 mmol?L~(-1)),a Kv channel blocker significantly decreased constriction of rat isolated PA rings induced by 15-KETE,and results were similar in two groups;(3) The K_(ATP) channel blocker glyburide(10~(-6)6 mol?L~(-1)) and the BK_(Ca) channel blocker tetraethylammonium(10 mmol?L~(-1)) did not affect constriction of rat isolated PA rings induced by 15-KETE;(4) The BKCa channel blocker nifedipine(10~(-6) mol?L~(-1)) and Ca~(2+)-free Krebs solution significantly decreased constriction of rat isolated PA rings induced by 15-KETE.Conclusion Kv channels play a role in constriction of PA induced by 15-KETE;L-type Ca~(2+) channel blocker and extracellular calcium ion also influence constriction of isolated PA rings induced by 15-KETE.