Effect of SJAMP on Human Platelet Cytoplasmic Ca^(2+)

Using the method of dual-wavelength measurement of platelet [Ca2+]i, and Fura-2 as the Ca2+ fluorophore probe, we measured the effect of acidic Mu-copolysaccharide from Sticopus Japonicus Selenka (SJAMP) on platelet [Ca2+]i. The results showed that the most significant increase in platelets [Ca2+]i was seen when the concentration of SJAMP was 100μg/ml and the elevation of normal platelet [Ca2+]i was 93. 96±10. 24 nmol/L (n = 10). In the presence of extracellular Ca2+(1 mmol/L), the magnitude of platelet [Ca2+]i response to SJAMP was increased and the [Ca2+]i, could reach 116. 72 + 10. 66 nmol/L (n= 10). On the other hand, the magnitude of increased platelet [Ca2+]i; induced by SJAMP was smaller and the duration of [Ca2+]i reaching the highest level was longer when compared with other platelet aggregation agents. In the mean time, if platelets were first incubated with cyclooxygenase inhibitor, the rise of [Ca2+]i evoked by SJAMP was inhibited. The results indicated that the mechanism of the rise of [Ca2+]i induced by SJAMP might be dependent upon the generation of prostaglandin endoperoxides and (or) TXA?.

The key target of neuroprotection after the onset of ischemic stroke: secretory pathway Ca^(2+)-ATPase 1

The regulatory mechanisms of cytoplasmic Ca2＋ after myocardial infarction-induced Ca2＋ overload involve secretory pathway Ca2＋-ATPase 1 and the Golgi apparatus and are well understood. However, the effect of Golgi apparatus on Ca2＋ overload after cerebral ischemia and reperfusion remains unclear. Four-vessel occlusion rats were used as animal models of cerebral ischemia. The expression of secretory pathway Ca2＋-ATPase 1 in the cortex and hippocampus was detected by immunoblotting, and Ca2＋ concentrations in the cytoplasm and Golgi vesicles were determined. Results showed an overload of cytoplasmic Ca2＋ during ischemia and reperfusion that reached a peak after reperfusion. Levels of Golgi Ca2＋ showed an opposite effect. The expression of Golgi-specific secretory pathway Ca2＋-ATPase 1 in the cortex and hippocampus decreased before ischemia and reperfusion, and increased after reperfusion for 6 hours. This variation was similar to the alteration of calcium in separated Golgi vesicles. These results indicate that the Golgi apparatus participates in the formation and alleviation of calcium overload, and that secretory pathway Ca2＋-ATPase 1 tightly responds to ischemia and reperfusion in nerve cells. Thus, we concluded that secretory pathway Ca2＋-ATPase 1 plays an essential role in cytosolic calcium regulation and its expression can be used as a marker of Golgi stress, responding to cerebral ischemia and reperfusion. The secretory pathway Ca2＋-ATPase 1 can be an important neuroprotective target of ischemic stroke.

Action Mechanism Research of Lanthanons to Slow Vacuolar Ion Channels in Raphanus Satirus L.(Xinlimei) Radish by Patch-Clamp

We used whole-vacuolar patch-clamp recording mode to study the action mechanism of La3+ to Slow Vacuolar (SV) channels for the first time. We recorded SV channel currents of Xinlimei (Raphanus satirus L.) vacuolars. The minimum activation potentials of voltage-dependent SV channels tied in 25+/-5 mV. The increase in cytoplasmic Ca2+ led to enhancement of SV-type currents. It was found that the threshold potential of activation shifted towards more depolarized values whenever cytoplasmic Ca2+ was increased. When 10(-10) mol/L free La3+ was added to the bath, SV-type current was suppressed by 60 similar to 75%. These data showed La3+ reduced ion permeabilities of Xinlimei root vacuolar membrane.