[The effect of batroxobin on coronary segmental resistance and coronary blood flow in acute myocardial ischemic dogs].

To study the effects of batroxobin on coronary circulation and cardiac performance in acute myocardial ischemia, Batroxobin was given intravenously to dogs with experimental coronary stenosis. A dose-dependent increase of coronary blood flow (CBF) was observed. Forty minutes after batroxobin (2 BU.kg-1 at infusion rate 0.1 BU.kg-1.min-1) administration, CBF increased by 12% (P < 0.05), small coronary resistance(RS) decreased from 4.1 +/- 0.5 to 3.2 +/- 0.5 mmHg.min.ml-1 (P < 0.01), while large coronary resistance(RL) changed insignificantly from 3.9 +/- 0.8 to 3.8 +/- 0.7 mmHg.min.ml-1 (P > 0.05). Two hours following drug administration, the changes in CBF, RS and RL still remained and RT decreased by 13% (P < 0.05). The + LV(dp/dt)max and -LV(dp/dt)max increased by 14% and 16% (P < 0.05) respectively compared with those in control group. It is concluded that batroxobin improves the ischemic canine coronary circulation and cardiac performance by way of lowering the small coronary resistance and thus increasing CBF. The data also suggest the benificial effect of batroxobin in acute myocardial ischemia.

Synthesis and biological activity of atriopeptin III and its small molecular analog.

Atriopeptin III (AP III) and its small molecular analog were synthesized manually by stepwise solid-phase method. The peptides were oxidized with iodine in 30% acetic acid at very high dilution to form intramolecular disulfide bridge and purified to homogeneity by conventional means, including Sephadex G15, dialysis and reversed-phase HPLC. Bioassay study demonstrated that the synthetic AP III possesses potent bioactivities identical to those of the same product of Peninsula Lab both in vitro and in vivo; whereas the linear peptide, having the same primary structure as AP III, showed very limited bioactivity. The small analog, with Ser-Ser-residue deleted from the N-terminal of AP III, was equipotent as AP III while exhibiting a longer half-life in vivo resulting from the peptide modification.

[Effects of tetraethylammonium chloride and verapamil on the effective refractory period of ischemic myocardium in rabbits].

The effects of potassium ion channel blocker TEA and calcium ion channel blocker verapamil on effective refractory period (ERP) of ischemic ventricular muscle were studied in rabbits. The results showed that ERP of the ventricular muscle in central ischemic zone (CIZ) and border ischemic zone (BIZ) were shortened, respectively, at 10 min and 30 min after coronary occlusion (P < 0.01). The changes of ERP in TEA-treated and verapamil-treated rabbits after coronary occlusion were found to be significantly less than those in untreated rabbits. The results suggest that TEA and verapamil alleviated the degree of ERP shortening after coronary occlusion and may exhibit protective effects on the ischemic myocardium.