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Objective: To study the effect and the mechanism of acute hypoxia on Ca2+-ATPase inhibitor, cyclopiazonic acid (CPA) induced intracellular calcium cation enhancement in rat distal pulmonary venous smooth muscle cells (PVSMC) . Methods: The PVSMC were isolated from 6 male SD rats and the cells were cultured for further experiment. Enhancing effects of CPA, acute hypoxia (4% O2) on [Ca2+]i in distal PVSMC and the interventional effects of 2 store-operated Ca2+ channels (SOCC) inhibitors, NiCl2 and SKF96365 on [Ca2+]i in distal PVSMC were tested by lfuorescence microscope and intracellular [Ca2+] examining system. Results: When PVSMC were perfused with Ca2+-free Krebs solution containing 5 μmol/L nifedipine, 10 μmol/L CPA caused a slight elevation of [Ca2+]i, and acute hypoxia obviously enhanced the [Ca2+]i in PVSMC. When restoration of extracellular [Ca2+] to 2.5 mmol/L, 10 μmol/L CPA caused signiifcant elevation of [Ca2+]i, and acute hypoxia obviously enhanced [Ca2+]i induced by CPA in PVSMC. The SOCC inhibitors, NiCl2 (500 μmol/L) and SKF96365 (50 μmol/L) distinctively attenuated the elevation of [Ca2+]i by hypoxia and CPA. However, NiCl2 and SKF96365 had no effect on high potassium (60 mmol/L KCl Krebs solution) induced elevation of [Ca2+]i in distal PVSMC. Conclusion: Acute hypoxia enhanced the elevation of [Ca2+]i induced by CPA; such effect could be selectively blocked by SOCC inhibitor which indicated that acute hypoxia could enhance the activity of SOCC in rat distal PVSMC.
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Objective To study the effect of SKF96365 and NiCl2 on cyclopiazonic acid (CPA) induced intracellular calcium cation concentration ([Ca2+ ]i ) change in rat distal pulmonary arterial smooth muscle cells (PASMC) .Methods The rat distal PASMC were isolated and cultured .The effects of CPA ,SKF96365 and NiCl2 on [Ca2+ ]i in PASMC were tested by fluorescence microscope and InCyte [Ca2+ ]i measurement system .Results PASMC were incubated with Ca2+‐free Krebs solution containing 5μmol/L nifedipine ,10 μmol/L CPA caused a small transient increase in [Ca2+ ]i ;after restoration of extracellular Ca2+ to 2 .5 mmol/L ,10 μmol/L CPA caused marked increases in [Ca2+ ]i in PASMC incubated with Krebs solution containing 5 μmol/L nife‐dipine .Both 50 μmol/L SKF96365 and 500 μmol/L NiCl2 distinctly attenuated the increases in [Ca2+ ]i caused by 10 μmol/L CPA in PASMC .However ,neither 50 μmol/L SKF96365 nor 500 μmol/L NiCl2 affected the increases in [Ca2+ ]i caused by 60 mmol/L KCl in PASMC .Conclusion CPA induced increases in [Ca2+ ]i may related to Ca2+ release from sarcoplasmic reticulum and the in‐flux of Ca2+ through store‐operated Ca2+ channels (SOCC) in rat distal PASMC .Both SKF96365 and NiCl2 could selectively block SOCC and attenuated the influx of Ca2+ through SOCC in PASMC .
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AIM To study the characteristics of Ca 2+ channel mediated store operated Ca 2+ influx on rat vascular smooth muscle. METHOD Fura 2 fluorescence technique was used to investigate the [Ca 2+ ] i change. RESULTS ① S nitrosocaptopril (CapNO,20~120 ?mol?L -1 ) produced a concentration dependent inhibitory effect on cyclopiazonic acid(CPA) induced [Ca 2+ ] i change. The maximal inhibitory effect(37%?17%) of CapNO was reached at a concentration of 80 ?mol?L -1 . The same concentration of Captopril had no effects. ② Inhibition rate of 80 ?mol?L -1 CapNO (The concentration of maximal effect, CME) on CPA induced [Ca 2+ ] i change was 30%?10%, subsequent addition of 1 ?mol?L -1 Nif (CME)did not further produced the decrease effect (54%?18%). subsequent addition of 20 ?mol?L -1 SK&F96365 (CME) further produced the decrease effect. The inhibitory effects of 20 ?mol?L -1 SK&F96365 were significantly different in the cases of CapNO and Nif pretreatment(24%?10%) and non treatment (54%?11%). ③ The inhibitory effects of 2 ?mol?L -1 tyrphostinAG490(AG490,CME) were significantly different in the cases of CapNO (CME) pretreatment (24%?9%)and non treatment (42%?10%). 80 ?mol?L -1 CapNO effect on CPA induced [Ca 2+ ] i changes in AG490 pretreatment condition(18%?7%) was different from that in non treatment case(37%?10%). CONCLUSION S nitrosocaptopril obviously inhibits the opening of SOCC and VDCC, which mediates store operated Ca 2+ influx. The inhibitory effects of CapNO is associated with both sensitive to and non sensitive to tyrosine kinase (Janus2).