[Role of C-type natriuretic peptide receptor and large-conductance calcium-activated potassium channels in brain natriuretic peptide-induced porcine coronary artery dilation].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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]. CONCLUSION: BNP could relax the porcine coronary arterial smooth muscles by increasing BK(Ca) current, and this effect is not mediated by NPR-C.

[Sodium channel changes in human atrial cells isolated from various ages].

OBJECTIVE: To investigate if the increased incidence of atrial fibrillation with age was associated with changes of Na(+) channel in atrial myocytes. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Vasodilatory effects of CNP on aortic arteries of rabbits].

OBJECTIVE: To investigate the mechanism of vasodilatory effects of C-type natriuretic peptide (CNP). METHODS: Tension changes in aortic rings of rabbits were recorded with the presence of CNP or C-type natriuretic peptide receptor (NPR-C) agonist (cANF4-23) after pretreatment with epinephrine (NE) or 60 mmol/L KCl. The vasodilatory effects of four types of potassium channel blocker and NPR-C antagonist (cANF4-28) were also tested. RESULTS: A maximal vasorelaxant effects of (33.5 +/- 5.9) % and (38.4 +/- 10.6)% were recorded in the presence of 1 micromol/L CNP and cANF4-23, respectively, cANF4-28 attenuated the action of CNP [(19.8 +/- 8.3)%]. The vasorelaxant effects of CNP and cANF4-23 decreased significantly after pretreatment with 60 mmol/L KCl (P < 0.01). Glibenclamide and BaCl2 also attenuated the relaxant activities of CNP (P < 0.05). But only BaClZ decreased the vasodilatory action of cANF4-23 (P < 0.05). CONCLUSION: The relaxant activity of CNP is mediated through three paths: NPR-B/KATP, NPR-C/KIR and NPR-C/calcium channels.

[Efficacy of selective continuous transarterial infusion chemotherapy on advanced pancreatic cancer].

BACKGROUND & OBJECTIVE: Advanced pancreatic cancer is mainly treated by chemotherapy with poor prognosis. This study was designed to evaluate clinical efficacy and application of selective continuous transarterial infusion chemotherapy in treating patients with advanced pancreatic cancer. METHODS: Twenty patients with advanced pancreatic cancer were treated by selective continuous transarterial infusion chemotherapy. The interventional treatment was performed with Seldinger technique,12 patients received percutaneous femoral artery cannulization and catheter retention, 8 received percutaneous left subclavian artery port-catheter system implantation. Chemotheraputic drugs were continuously infused when the catheter was selectively placed in turner feeding artery. Nine patients were treated with pirarubicin (THP)/adriamycin (ADM) plus hydroxycamptothecin (HCPT),and 5-fluorouracil (5-FU)/calcium folinate (CF) regimen,and 11 were treated with gemcitabine (GEM) plus carboplatin (CBP),and 5-FU/CF regimen. Treatment regimens were repeated every 4-6 weeks with each cycle of 4 days. Tumor response rate,clinical benefit response (CBR),and survival time were observed. RESULTS: Objective response rate was 10% with 1 case of complete remission (CR), and 1 case of partial remission (PR), CBR was 70% (14/20), 6-,and 9-month survival rates were 58.8%,and 39.2%. Median survival time for all patients was 8.8 months. No complication related to cannulization was found. CONCLUSION: Selective continuous transarterial infusion chemotherapy is safe,and has good efficacy in treating patients with advanced pancreatic cancer, it may prolong survival time of patients.