M. Ishiki

Lipoprotein lipase activity in ischaemic and anoxic myocardium.

Myocardial lipoprotein lipase (LPL) activity during ischaemia has not been fully understood, although it plays an important role in regulating myocardial fatty acid metabolism. In this experiment, the effects of ischaemia (Experiment A) and anoxia (Experiment B) on two distinct fractions of LPL, i.e. functional and nonfunctional forms were investigated in isolated, perfused rat heart. In Experiment A, hearts were perfused by Neely-Morgan working heart mode with Krebs Henseleit bicarbonate (KHB) buffer (95% O2:5% CO2), then whole heart ischaemia was induced by using a one-way aortic valve, simultaneously switching to the same buffer but containing heparin (5 mu/ml) for 20 min. In Experiment B, the hearts were perfused by Langendorff method with KHB buffer (95% O2:5% CO2) and the buffer was switched to KHB (95% N2:5% CO2) containing heparin for 20 min. Coronary effluent was collected at 5 min intervals and used for the measurement of functional LPL activities using 3H-glyceryltrioleate. The hearts were quickly frozen at the end of perfusion and homogenized. The suspension was used for the measurement of non-functional LPL activities. In Experiment A, functional LPL activities in ischaemia were significantly lower than in the aerobic condition. On the contrary, the nonfunctional LPL activity in ischaemia was significantly higher than in the aerobic condition. In Experiment B these values were also significantly lower than in the aerobic condition. However, there was no significant difference in non-functional LPL activity between the anoxia and aerobic condition. These results indicate that there is a conversion defect from the precursor of LPL to the functional form of LPL in ischaemia, whereas disturbed LPL synthesis might be involved in anoxic myocardium.

Adhesive Effect of Ecabet Sodium in a Porcine Gastric Leer Model

Abstract: Protection of the gastric mucosa, based on its high affinity for mucosal lesions, has been reported as one of the antiulcer effects of ecabet sodium. We investigated the adhesive effect of this drug on mucosal lesions in a porcine gastric ulcer model (freshly isolated stomach) and on human mucosal lesions resulting from endoscopic gastric mucosal resection (EMR) and polypectomy. After ulcer lesions had been induced by EMR in the isolated porcine stomach, ecabet sodium and sucralfate suspensions were applied. After washing with citrate buffer, at a pH of 1, 3 or 5, the adhesion of each drug to the gastric mucosa was measured. At pH 1, both drugs showed satisfactory adhesion to the ulcer lesions. When the acidity of the ulcer surfaces was decreased to pH 3 and then to pH 5, the adhesion of sucralfate showed a marked decrease (100%→31→% 13%). while that of ecabet sodium showed only a slight decrease (100%→75%→64%). Futhermore, the activity of thrombin in the ecabet sodium suspension remained high at pH 1, 3 and 5. Since the ecabet sodium suspension produced a satisfactory covering effect on gastric mucosal lesions and this effect was maintained even at low acidity, this drug is considered suitable for endoscopic directsprinkling therapy for gastric mucosal lesions.