ABSTRACT
The Ca2+-ATPase of sarcoplasmic reticulum is a Ca2+ pump that plays a key role in regulating cytosol calcium concentration in muscle cells. It undergoes a sequential conformational transition during the transport process. According to the classical E1/E2 theory, in the E1 state the binding sites have high affinity and open to the cytoplasm, whereas in the E2 state the binding sites have low affinity and face the luminal side. Crystal structures of several states during the reaction cycle of Ca2+-ATPase have been solved recently, including a Ca2+-bound form (E1-2Ca2+), a Ca2+-unbound form stabilized by a potent inhibitor thapsigargin (TG) (E2-TG), an ATP-bound form (E1-ATP), an E1-P-ADP state, and an E2-Pi state. The details of these crystal structures and the relationship between structure and function of Ca2+-ATPase during reaction cycle were summarized, and the issues to be addressed in future research were raised.
ABSTRACT
AIM To observe the effect of quateranary ammonium salt derivative (F2) of haloperidol on calcium level in vascular smooth muscle cells (VSMCs) isolated from thoracic aortas of rat. METHODS VSMCs were loaded with Fluo-3-AM, a calcium sensitive fluorescent dye, and ［Ca2+］i was determined by the use of laser scanning confocal microscope (LCSM). RESULTS In Ca2+ (1.26 mmol*L-1) bath solution, intracellular calcium fluorescent intensity (FI) in VSMCs was increased when application with 30 mmol*L-1 KCl, and then was inhibited after addition with F2. The FI of the ASMCs with different concentrations of F2 (0.1,1,10,100 μmmol*L-1)within three minutes were 64%±9%(n=16, P<0.05),16%±5%(n=20, P<0.01),0.6%±0.8%(n=20, P<0.01),0.1%±0.3%(n=15, P<0.01), respectively. CONCLUSION F2 could decrease the intracellular Ca2+ level in the VSMCs by blocking the voltage-dependent calcium channel.
ABSTRACT
AIM To observe the effect of quateranary ammonium salt derivative (F 2) of haloperidol on calcium level in vascular smooth muscle cells (VSMCs) isolated from thoracic aortas of rat. METHODS VSMCs were loaded with Fluo 3 AM, a calcium sensitive fluorescent dye, and [Ca 2+ ] i was determined by the use of laser scanning confocal microscope (LCSM). RESULTS In Ca 2+ (1 26 mmol?L -1 ) bath solution, intracellular calcium fluorescent intensity (FI) in VSMCs was increased when application with 30 mmol?L -1 KCl, and then was inhibited after addition with F 2. The FI of the ASMCs with different concentrations of F 2 (0 1,1,10,100 ?mmol?L -1 )within three minutes were 64%?9%( n =16, P
ABSTRACT
AIM To investigate the effect of N n butyl haloperidol iodide (F 2) on potassium currents in enzymatically isolated vascular smooth muscle cells (VSMC) from thoracic aortas and the effect of F 2 on aortic rings of rat. METHODS The whole cell patch clamp technique and the contraction of rats thoracic aortic rings were used in experiments. RESULTS The outward currents were observed when holding potential was -40 mV and the cell was depolarized from -30 mV to +100 mV (in 10 mV increase) for 400 ms. At the point of the test potential of +70 mV, solutions of F 2 (0 1,1, 5 ?mol?L -1 ) were added into bath (external) solution, which led to the increase of the outward currents from (229?28)pA,(226?57)pA and(228?42) pA to (354?29) pA ( n =6, P