Effects of tetrandrine on cytosolic free calcium concentration in corpus cavernosum smooth muscle cells of rabbits / 亚洲男科学杂志(英文版)

ABSTRACT

<p><b>AIM</b>To study the relaxation mechanisms of tetrandrine (Tet) on the corpus cavernosum smooth muscle.</p><p><b>METHODS</b>The corpus cavernosum smooth muscle cells from New Zealand white rabbits were cultured in vitro. [Ca(2+)](i) was measured by Fluorescence Ion Digital Imaging System, using Fluo-2/AM as a Ca(2+)-sensitive fluorescent indicator.</p><p><b>RESULTS</b>Tet (1, 10 and 100 micromol/L) had no effect on the resting [Ca(2+)](i) (P>0.05). In the presence of extracellular Ca(2+) (2.5 mmol/L), Tet (1, 10 and 100 micromol/L) inhibited [Ca(2+)](i) elevation induced by high K(+) and phenylephrine (PE) in a concentration-dependent manner (P>0.05). In calcium free solution containing egtaic acid, Tet (1 and 10 micromol/L) had no inhibitory effects on [Ca(2+)](i) elevation induced by PE (P>0.05). However, Tet (100 micromol/L) inhibited [Ca(2+)](i) elevation induced by PE (P>0.05).</p><p><b>CONCLUSION</b>Tet inhibited the Ca(2+) influx from the extracellular site via voltage-activated Ca(2+) channel and alpha(2)-adrenoceptor-operated Ca(2+) channel. At a high concentration, Tet might inhibit the cytosolic calcium pool release in cultured corpus cavernosum smooth muscle cells. This inhibitory action on [Ca(2+)](i) might be one of the relaxation mechanisms of Tet on the corpus cavernosum smooth muscle.</p>