Animals ; Escin ; pharmacology ; Intestines ; blood supply ; Lipid Peroxidation ; drug effects ; Male ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; physiopathology ; prevention & control

OBJECTIVETo establish a perforated patch-clamp technology with amphotericin B and beta-escin and to research the regulation of small conductance calcium-activated potassium channel SK2 currents by calcium ions.

METHODSSingle human atrial myocytes were enzymatically isolated from the right atrial appendage. Amphotericin B and / or beta-escin were used by perforated electrode liquid. The regulation of SK2 current by calcium ions in human atrial myocytes was performed with the perforated patch-clamp technique. The intracellular calcium changes were measured by the intracellular calcium test system.

RESULTSMixed perforated electrode liquid compared with 150 microg/ml amphotericin B or 6.88 microg/ml beta-escin alone, it was easy to seal cells and activate SK2 current by the former method. Moreover, the ration of F340/380 was consistent with the change of intracellular free calcium ion concentration increase after the formation of perforation. The ration of F340/380 was measured by intracellular calcium test system.

CONCLUSIONThe appropriate concentration of amphotericin B mixed with beta-escin can form a stable whole-cell patch recording technology that is appropriate for the research of SK2 current regulation by intracellular calcium.

Amphotericin B ; pharmacology ; Calcium ; metabolism ; Electric Conductivity ; Escin ; pharmacology ; Humans ; Myocytes, Cardiac ; physiology ; Patch-Clamp Techniques ; Potassium Channels, Calcium-Activated ; drug effects

To elucidate the Ca2+ release mechanisms in the rabbit coronary artery, arterial preparations were permeabilized with beta-escin and changes in tension were measured under varying experimental conditions. Additionally, we investigated properties and distribution of two kinds of Ca2+ release mechanisms, Ca2+-induced Ca2+ release (CICR) and IP3-induced Ca2+ release (IICR). The results obtained were summarized as follows; 1. When a rabbit coronary artery was incubated in a relaxing solution containing 30 microM beta-escin for 40 min. sensitivity to externally added Ca2+ was much higher in beta-escin permeabilized muscle than in intact preparations. The contractile effect of IP3 in beta-escin permeabilized muscle was also demonstrated; 2. Caffeine and IP3 contracted coronary arteries were permeabilized with beta-escin, but the amplitude of contraction was much larger in the presence of caffeine than of IP3. 3. Intracellular heparin completely inhibited the contractions induced by IP3, but not those by caffeine. On the other hand, procaine inhibited the responses to caffeine, but not those to IP3. Ryanodine inhibited both the caffeine- and IP3-induced contractions. 4. The amplitude of contractile responses was much larger to the maximal stimulation of CICR by applying caffeine than to the maximal stimulation of IICR by applying IP3. After the maximal CICR stimulation by caffeine, the activation of IICR by IP3 without the reloading of Ca2+ could no longer evoke contraction. On the other hand, after the maximal IICR activation, the activation of CICR could still evoke contraction although the amplitude of the contraction was smaller when compared with the case without the initial IICR stimulation. 5. Acetylcholine contracted coronary artery smooth muscles were permeabilized with beta-escin. However, in the absence of added guanosine triphosphate (GTP), the responses were very small. Acetylcholine-induced contraction was inhibited by heparin, but not by procaine. From the above results, it may be concluded that there are two kinds of mechanisms of Ca2+ release, CICR and IICR, in the rabbit coronary artery smooth muscle cell. Also, whereas the CICR mechanism distributes on the membrane of the whole smooth muscle Ca2+ store, the IICR mechanism distributes only on a part of it.
Animal ; Arteries/metabolism ; Calcium/*metabolism ; Capillary Permeability/drug effects ; Coronary Vessels/drug effects/*metabolism ; Escin/pharmacology ; In Vitro ; Intracellular Membranes/*metabolism ; Rabbits ; Support, Non-U.S. Gov't ; Tissue Distribution

AIMTo investigate the protective effects of sodium beta-aescin on cerebral ischemia-reperfusion injury in rats.

METHODSRats were pretreated with sodium beta-aesein for 7 d and then subjected to cerebral ischemia-reperfusion injury induced by a middle cerebral artery occlusion (MCAO). The neurological outcome was evaluated by the Longa's method; The infarct volume was assessed by hemmatoxylin-Eosin staining and the cerebral water content was measured by dry weight method. The activities of SOD, GSH-Px, CAT, Na+ -K+ -ATPase and the MDA content were measured in the cortex and hippocampus of ischemic and non-ischemic hemisphere.

RESULTSSodium beta-aescin significantly reduced the volume of cerebral infarct and water content, and ameliorated the neurological deficit (P < 0.05). In vehicle-treated rats, the activities of SOD, GSH-Px and Na+ -K+ -ATPase in the cortex and hippocampus of ischemic hemisphere were all decreased (P < 0.01) , while the CAT activity was slightly elevated and the MDA of content was significantly increased (P < 0.01) compared with the sham-operated group. After treated with sodium beta-aescin, the effects on recovery of SOD, GSH-Px, Na+ -K+ -ATPase activities were observed (P < 0.05), and the MDA content was reduced (P < 0.05).

CONCLUSIONThese results showed that pretreatment with sodium beta-aescin can attenuate brain injury and its antioxidant activity on rats which encountered cerebral ischemia-reperfusion.

Animals ; Brain ; metabolism ; Brain Ischemia ; metabolism ; pathology ; Catalase ; metabolism ; Escin ; pharmacology ; Glutathione Peroxidase ; metabolism ; Male ; Malondialdehyde ; metabolism ; Neuroprotective Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; metabolism ; pathology ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Superoxide Dismutase ; metabolism