A new kalium channel blocker of Chinese medicinal origin —Benzyltetrahydropalmatine hydrochloride

Abstract

Benzyltetrahydropalmatine hydrochloride (BTHP) exhibited antiarrhythmic action in animal models. I. Electrophysiological effects of BTHP were investigated in various heart preparations. 1) BTHP markedly prolonged functional refractory period and inhibited adrenaline-induced automaticity. It decreased spontaneously beating rate of right atrium and abolished ouabain-induced delayed afterdepolarization and triggered activity of papillary muscle. 2) In standard microelectrode and contractility experiments BTHP concentration-dependently prolonged the action potential duration (APD) and effective refractory period (FRP) between 1-100 mumol/L; the force of contraction remained unchanged. 3) In voltage clamp experiments BTHP 1-100 mumol/L inhibited in dose-dependent manner the Ik with IC50 of 13 mumol/L and inhibited also Is at high concentration. 4) In monophasic action potential (MAP) of feline ventricle MAPD50 and MAPD90 were prolonged by BTHP in normal myocardium, and shortened APD induced by ischemia and reperfusion was restored to normal level. 5) In ECG and His-bundle electrogram heart rate was reduced; P-R and A-H interval were prolonged, but H-V interval and V duration were unaffected. II. BTHP showed a competitive alpha 1-adrenoceptor-blocking effect with pA2 value of 5.8 and 5.86 in rat anococcygeus muscle and rabbit aortic strips respectively. Radioligand binding assays showed that BTHP had affinity for both alpha 1 and alpha 2-adrenoceptor. The results from these experiments show that BTHP is a new K+ channel blocker of Chinese medicinal origin with alpha 1-adrenoceptor-blocking action.

The Whole Process Simulation and Research on Temperature Field and Thermal Stress for Large Sluice Pier

“…The sluice pier, as a typical pier-walled concrete structure, the cracking phenomenon occurs frequently. The cracking due to the temperature difference between inside and outside of the pier-wall, the temperature drop, the basic constraint, the concrete shrinkage and the self-volume deformation of concrete [1][2][3]. So far, it has been widely recognized that the thermal stress during construction period is one of the important reasons for the various types of cracks of sluice pier, so the temperature control [4] is the focus of the cracking prevention during construction period.…”