Role of C-type natriuretic peptide receptor and large-conductance calcium-activated potassium channels in brain natriuretic peptide-induced porcine coronary artery dilation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the role of C-type natriuretic peptide receptor (NPR-C) and large-conductance calcium-activated potassium channels (BK(Ca)) in brain natriuretic peptide (BNP) induced porcine coronary artery dilation.</p><p><b>METHODS</b>Porcine coronary artery rings were obtained and treated with BNP (10(-6) mol/L), BNP + NPR-C antagonist cANF4-28 (10(-6) mol/L) and BNP + BK(Ca) blocker tetraethylammonium (TEA, 1 mmol/L). The vascular tone experiments were observed on 10 vessel segments. BK(Ca) current density was measured by the whole-cell patch clamp technique.</p><p><b>RESULTS</b>The maximum diastolic rate was similar between BNP group (68.51% ± 11.50%) and cANF4-28 + BNP group (65.67% ± 11.90%, P > 0.05) while significantly reduced in TEA + BNP group (28.87% ± 4.55%, all P < 0.05). When the holding potential was set at +60 mV, the BK(Ca) current density of BNP group was (78.48 ± 5.86) pA/pF, which was significantly higher than control group [(53.84 ± 4.55) pA/pF, P < 0.05], which was equally reduced in the TEA group and TEA + BNP group [(28.80 ± 2.76) pA/pF and (30.60 ± 3.88) pA/pF respectively, all P < 0.05 vs. control group].</p><p><b>CONCLUSION</b>BNP could relax the porcine coronary arterial smooth muscles by increasing BK(Ca) current, and this effect is not mediated by NPR-C.</p>

Sodium channel changes in human atrial cells isolated from various ages / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate if the increased incidence of atrial fibrillation with age was associated with changes of Na(+) channel in atrial myocytes.</p><p><b>METHODS</b>Twenty-three patients underwent valve replacement operations were divided into adult [< 60 years, n = 15, 9 males, mean age (42.1 +/- 7.1) years] and aged group [> or = 60 years, n = 8, 5 males, mean age (63.3 +/- 3.1) years]. All patients were in normal sinus rhythm. Whole cell patch clamp techniques were used to record the Na(+) currents (I(Na)) of right auricle myocytes.</p><p><b>RESULTS</b>Both current density and time-dependent recovery of I(Na) were similar in the cells from the 2 groups. Voltage-dependent inactivation of I(Na) of myocytes in the aged atria was shifted to more positive voltages.</p><p><b>CONCLUSION</b>Current density of I(Na) was similar between the 2 age groups, and Na(+) channel might not be an important determinant for the increased incidence of atrial fibrillation in aged patients.</p>