Effect of protopine on contraction and intracellular free calcium concentration of smooth muscle of thoracic aorta in rats / 第三军医大学学报

ABSTRACT

Objective To study the effect of protopine (Pro) on the intracellular free calcium ions of the smooth muscular cells of the thoracic aorta in rats. Methods The procedure of calcium absence-calcium addition was designed to observe the changes of the level of calcium ions in the strips of the smooth muscle of the thoracic aorta indirectly. The concentration of calcium ions in the smooth muscle of the thoracic aorta was determined with Fura-2/AM loaded SMCs. The elevation of calcium ions was induced with norepinephrine (NE). The concentration of potassium ions was observed in the presence of Pro. Results Pro significantly inhibited the NE-induced transient contract of the smooth muscle of the thoracic aorta in calcium-free medium and long-lasting contraction after the addition of calcium ions in a concentration-dependent manner. In Fura-2/AM loaded SMCs, Pro (50 ?mol/L or 100 ?mol/L) exerted no effect on the resting calcium ions but obvious effect on the NE-induced and high potassium level-induced elevation of calcium ions. In the presence of extracellular calcium ions, Pro (50 ?mol/L) decreased the NE-induced elevation of calcium ions but showed no effect on potassium-induced elevation of calcium. Pro (100 ?mol/L) significantly decreased NE-induced and high potassium level-induced elevation of calcium ions. Conclusion Pro reduces NE-induced or high potassium level-induced elevation of calcium ions in the smooth muscle of the thoracic aorta through its effect on calcium release and/or calcium influx.