Stimulation of the calcium-sensing receptor induces relaxations of rat mesenteric arteries by endothelium-dependent and -independent pathways via BKCa and KATP channels.

Stimulation of the calcium-sensing receptor (CaSR) induces both vasoconstrictions and vasorelaxations but underlying cellular processes remain unclear. This study investigates expression and effect of stimulating the CaSR by increasing external Ca2+ concentration ([Ca2+ ]o ) on contractility of rat mesenteric arteries. Immunofluorescence studies showed expression of the CaSR in perivascular nerves, vascular smooth muscle cells (VSMCs), and vascular endothelium cells. Using wire myography, increasing [Ca2+ ]o from 1 to 10 mM induced vasorelaxations which were inhibited by the calcilytic Calhex-231 and partially dependent on a functional endothelium. [Ca2+ ]o -induced vasorelaxations were reduced by endothelial NO synthase (eNOS, L-NAME) and large conductance Ca2+ -activated K+ channels (BKCa , iberiotoxin), with their inhibitory action requiring a functional endothelium. [Ca2+ ]o -induced vasorelaxations were also markedly inhibited by an ATP-dependent K+ channel (KATP ) blocker (PNU37883), which did not require a functional endothelium to produce its inhibitory action. Inhibitor studies also suggested contributory roles for inward rectifying K+ channels (Kir ), Kv7 channels, and small conductance Ca2+ -activated K+ channels (SKCa ) on [Ca2+ ]o -induced vasorelaxations. These findings indicate that stimulation of the CaSR mediates vasorelaxations involving multiple pathways, including an endothelium-dependent pathway involving NO production and activation of BKCa channels and an endothelium-independent pathway involving stimulation of KATP channels.

Can Valeriana officinalis root extract prevent early postoperative cognitive dysfunction after CABG surgery? A randomized, double-blind, placebo-controlled trial.

RATIONALE: We hypothesized that valerian root might prevent cognitive dysfunction in coronary artery bypass graft (CABG) surgery patients through stimulating serotonin receptors and anti-inflammatory activity. OBJECTIVES: The aim of this study was to evaluate the effect of Valeriana officinalis root extract on prevention of early postoperative cognitive dysfunction after on-pump CABG surgery. METHODS: In a randomized, double-blind, placebo-controlled trial, 61 patients, aged between 30 and 70 years, scheduled for elective CABG surgery using cardiopulmonary bypass (CPB), were recruited into the study. Patients were randomly divided into two groups who received either one valerian capsule containing 530 mg of valerian root extract (1,060 mg/daily) or placebo capsule each 12 h for 8 weeks, respectively. For all patients, cognitive brain function was evaluated before the surgery and at 10-day and 2-month follow-up by Mini Mental State Examination (MMSE) test. RESULTS: Mean MMSE score decreased from 27.03 ± 2.02 in the preoperative period to 26.52 ± 1.82 at the 10th day and then increased to 27.45 ± 1.36 at the 60th day in the valerian group. Conversely, its variation was reduced significantly after 60 days in the placebo group, 27.37 ± 1.87 at the baseline to 24 ± 1.91 at the 10th day, and consequently slightly increased to 24.83 ± 1.66 at the 60th day. Valerian prophylaxis reduced odds of cognitive dysfunction compared to placebo group (OR = 0.108, 95 % CI 0.022-0.545). CONCLUSION: We concluded that, based on this study, the cognitive state of patients in the valerian group was better than that in the placebo group after CABG; therefore, it seems that the use of V. officinalis root extract may prevent early postoperative cognitive dysfunction after on-pump CABG surgery.