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Introduction: Functional interaction between K(ATP) channel and Na/K ATPase was studied in single guinea pig ventricular myocytes because both membrane molecules are known to be involved in ischemic episodes., Methods and Results: K(ATP) channel currents were recorded at 36 degrees C by using whole cell, cell-attached, inside-out, and open cell-attached modes of patch clamp techniques on enzymatically isolated ventricular myocytes. In the whole cell mode, ouabain (1 microM) reversibly inhibited the K(ATP) currents induced by metabolic stress (ATP-free pipette solution and 1 mM NaCN), but not those activated by cromakalim (100 microM), a K(ATP) channel opener. In the cell-attached mode, ouabain concentration dependently inhibited K(ATP) channel opening induced by metabolic suppression (5.5 mM 2-deoxyglucose and 1 mM CN-). Half-inhibition concentration for ouabain was 21.0 +/- 5.5 nM and the Hill coefficient was 0.8 +/- 0.1 (n = 26). However, ouabain did not have an effect on the channel activity induced by cromakalim (100 microM). In the inside-out mode, ouabain applied to the internal side of membrane did not affect the channel. In the open cell-attached mode made by preincubation with streptolysin-O (0.08 U/mL), the K(ATP) channels were not activated by the metabolic inhibitors but were by reducing extracellular ATP concentrations, because subsarcolemmal ATP concentration could be controlled through tiny membrane holes. The channels thus activated were not suppressed by ouabain., Conclusion: The inhibition of Na/K ATPase by ouabain appeared to block the K(ATP) channels by accumulating subsarcolemmal ATP caused by a decrease of the transition from ATP to ADP. In the presence of ischemic episodes, the administration of digitalis compounds may affect the opening of K(ATP) channels, which is primarily protective against the development of irreversible myocardial damage.

Based on field investigation and taxonomic research on the medicinal plants of Dipsacaceae in China, eighteen species and four varieties of five genera in this family are reported. Among them, some new medicinal plant resources are supplemented, the Latin name of one species is revised, the distribution, habitats and medicinal uses of the species are spelled out and a key for the genus of Dipsacus is given.

Cardiovascular drugs such as antiarrhythmic agents with Vaughan Williams class Ia action have been found to induce a sporadic hypoglycemia. Recent investigation has revealed that these drugs induce insulin secretion from pancreatic beta-cells by inhibiting ATP-sensitive K+ (KATP) channels in a manner similar to sulfonylurea drugs. The mechanism underlying block of KATP channels by antiarrhythmic drugs was different, however, from that of sulfonylureas: firstly, because binding of radioactive glibenclamide could not be inhibited by unlabelled antiarrhythmic agents, and vice versa; secondly, because the two compounds differ in the kinetics and sidedness of drug action-antiarrhythmic drugs act on the channel from the inner surface of the cell membrane, whereas glibenclamide binds through the intramembrane pathway; finally, it was shown that functional KATP channels in beta-cells are composed of two distinct molecules-a sulfonylurea receptor (SUR) and a channel pore-forming subunit, an inwardly-rectifying K channel with two transmembrane regions (Kir6.2). Antiarrhythmic drugs reversibly inhibit the K+ conductance displayed by the Kir6.1 (a putative KATP channel clone)-transfected NIH3T3 cells. Therefore they appear to interact directly with the pore-forming subunit, thereby inhibiting KATP channel currents and exerting an insulinotrophic effect.

Objectives: To clarify the relationship between open heart surgery and gallstone formation., Methods: Fifty-one patients without gallstones (Group A) underwent cardiac surgery using a heart-lung machine and were followed for 24 months by ultrasonography. Blood tests of hemolysis markers were examined before, immediately after, and 3, 6, and 12 months after surgery. And 52 healthy candidates without gallstone (Group B) also were followed for 24 months., Results: The cumulative gallstone incidence in Group A was 15.7% at 3 months after surgery, 23.9% at 6 months, and 30.4% at and beyond 12 months and was significantly higher than that of Group B (p < 0.01). The stones showed a high dense pattern, indicative of pigment stones, in eight of the 10 patients assessed by CT. With respect to the type of surgery, latent hemolysis was seen only in patients who underwent mechanical valve replacement. However, there were no significant differences in the gallstone incidence between the patients who underwent mechanical valve replacement and those who underwent another cardiac surgery. The values of hemoglobin, haptoglobin, and lactate dehydrogenase showed abnormal values immediately after surgery, regardless of mechanical valve replacement or another cardiac surgery., Conclusions: The use of a heart-lung machine, which produces hemolysis, appears to have a close relation to gallstone formation after open cardiac surgery.

The contents of dryocrassin in Rhizoma Dryopteris Crassirhizomae were determined by TLC-scanning in a period of two years of storage. Phloroglucinol content was calculated by area normalization method. The results show that in contrast with the fresh crude drugs of Rhizoma Dryopteris Crassirhizomae, the contents of dryocrassin in the crude drugs of one year and two years of storage have reduced by 22% and 27% respectively, and phloroglucinol contents have reduced by 2% and 8% respectively.

1. We investigated the effect of cibenzoline (a class Ia antiarrhythmic drug) on basal insulin secretory activity of rat pancreatic islets and ATP-sensitive K+ channels (KATP) in single pancreatic beta cells of the same species, using radioimmunoassay and patch clamp techniques. 2. Micromolar cibenzoline had a dose-dependent insulinotrophic action with an EC50 of 94.2 +/- 46.4 microM. The compound inhibited the activity of the KATP channel recorded from a single beta-cell in a concentration-dependent manner. The IC50 was 0.4 microM in the inside-out mode and 5.2 microM in the cell-attached mode, at pH 7.4. 3. In the cell-attached mode, alkalinization of extracellular solution increased the inhibitory action of cibenzoline and the IC50 was reduced from 26.8 microM at pH 6.2 to 0.9 microM at pH 8.4. On the other hand, the action of cibenzoline in the excised inside-out mode was acute in onset with a small IC50, indicating that the drug attains its binding site from the cytoplasmic side of the cell membrane. 4. In the inside-out mode, micromolar ADP reactivated the cibenzoline-blocked KATP channels in a manner similar to that by which ADP restored ATP-dependent block of the channel. 5. The binding of [3H]-glibenclamide to pancreatic islets was inhibited by glibenclamide but not by cibenzoline. In contrast, the [3H]-cibenzoline binding was displaced by unlabelled cibenzoline but not by glibenclamide. It is concluded that cibenzoline blocks pancreatic KATP channels via a binding site distinct from the sulphonylurea receptor.

By on-the-spot investigation we have checked up on 8 kinds of botanical origin of the Chinese traditional drug Guanzhong produced in East China and have given keys for their identification. The major tissue features of basal petioles and the external characteristics of the crude drugs have also been given.