*4.5. Study of Vasorelaxant Mechanisms of B. monnieri Active Compounds on Extracellular Ca2*<sup>+</sup> *Influx*

Endothelial denuded mesenteric arteries were equilibrated in Ca2+-free Krebs' solution (containing (mM): ethylene glycol-bis (ß-aminoethyl ether)-N,N,N,N tetra acetic acid (EGTA), 0.01; NaCl, 122; KCl, 5; HEPES, 10; KH2PO4, 0.5; NaH2PO4, 0.5; MgCl2, 1 and glucose, 11 (pH 7.3)) for 30 min followed by replacing with Ca2+-free Krebs' solution containing 80 mM K<sup>+</sup> for 10 min which depolarizes the vascular smooth muscle cells, thus opening VOCCs. Various concentrations of CaCl2 were then added (0.01–10 mM) in a logarithmic progression. After obtaining the maximum response, the baths were washed out and replenished with Ca2+-free Krebs' solution for 30 min. The Ca2+-free 80 mM K<sup>+</sup> solution was then re-applied following pre-incubation for 10 min with either: 10 μM active compounds or 1 μM nicardipine (antagonist of VOCCs). Concentration-response curves to cumulative addition of CaCl2 were then repeated and compared with maximum contraction evoked by previous control CaCl2 challenges.
